Even the most stable Android smartphone begins to “glitch” over time: applications crash, the system slows down, the battery runs out within an hour, and sometimes the device refuses to turn on at all. The reasons may lie in both software failures (damaged files, conflicting applications, viruses) and hardware failures (battery wear, processor overheating, memory problems). But how can you understand what exactly went wrong without contacting a service center?

In this article we will look at 7 proven diagnostic methods from built-in Android tools to hidden engineering menus and third-party utilities. You will learn how to read log files systems, test hardware without disassembling the device, and what to do if you have a smartphone stopped loading after updating the firmware. And also - how to distinguish a software bug from a hardware failure, so as not to waste money on unnecessary repairs.

1. Built-in Android tools: where to look for errors without third-party apps

Android hides a lot of diagnostic information, but you can get to it through the standard settings. Let's start with the simplest thing - checking error logs and system reports.

Open Settings → System → About phone (on some firmware the path may differ: Settings → About device → Software information). Here you are interested in two sections:

  • 📊 Build number - tap on it 7 times to activate Developer mode (needed for the following steps).
  • 🔍 Device status — if “Not certified” is indicated here, this may indicate unofficial firmware or root access, which often leads to failures.

Now return to the main settings menu and find the new section For developers (or Developer options). Here:

  • 📱 Enable USB debugging —this will allow you to connect your smartphone to a PC for deep diagnostics.
  • 🐞 Activate Error log (Enable bug report shortcut) - now when you hold the power button, the option to create an error report will appear.
  • 📈 Enable GPU acceleration i Displaying CPU load — this will help track processor overload.
⚠️ Attention: If in the section For developers you see a warning “OEM unlocking enabled”, this means that the bootloader unlocked Such devices are more vulnerable to viruses and may not receive OTA updates.

To quickly check system stability, run performance test:

  1. Go to Settings → Battery → Battery usage.
  2. See which applications consume the most energy - if unknown services are in the top (for example, com.android.system with abnormal consumption), this is a sign of a virus or a background glitch.
  3. Open Settings → Memory and check how much space the cache and system datatake up. If less than 10% is free, the system will slow down.
📊 How often do you check your smartphone for errors?
Only when something broke
Once a month
Once every six months
Never

2. How to read Android logs: finding the causes of failures in system logs

Android log files contain detailed information about all processes, including application errors, system crashes and hardware failures. They can be viewed both on the device itself and through a computer.

Method 1: through the app Logcat (without root)

Install from Google Play utility Logcat Reader or aLogcat. After launch:

  1. Select a filter Error (errors) or Warning (warnings).
  2. Look for lines with keywords:
    • 🔴 ANR (Application Not Responding) - application froze.
    • 🔴 NullPointerException —critical error in the code.
    • 🔴 BatteryStats —problems with energy consumption.
    • 🔴 ThermalEngine —processor overheating.
  • Copy suspicious logs and check them through a search (for example, enter in Google site:stackoverflow.com "your error").

    • Method 2: Via ADB (advanced method)

    If you have a computer, connect your smartphone via USB (with enabled USB debugging) and use the command:

    adb logcat -d | findstr "E"

    This the command will display all errors (Error) for the last session. To save the log to a file:

    adb logcat -d > android_logs.txt
    ⚠️ Attention: Logs may contain confidential information (phone numbers, file paths). Do not share them in open sources without first clearing them.
    Log type What does it mean How to fix
    ANR in com.android.systemui The system interface (launcher, notification panel) is frozen. Clear cache Settings → Applications → System UI → Memory → Clear cache.
    java.lang.OutOfMemoryError The application does not have enough RAM. Close background processes or reboot the device.
    BatteryStats: discharge rate = X mAwhere X > 500 Abnormal battery discharge (possibly a virus or faulty battery). Check the consumption list in Settings → Battery.
    Thermal: temperature = X°C, where X > 60 Overheating of the processor (risk of throttling or shutdown). Close resource-intensive applications, check the thermal paste (if you disassembled the device).
    💡

    If an error occurs frequently in the logs PackageManager: Not installing package, try clearing the cache and data Google Play Market and Google Play Services in application settings.

    3. Hardware testing: how to check hardware components

    If the smartphone slows down, reboots spontaneously or does not turn on, the problem may lie in hardware: a worn-out battery, faulty memory or overheating of the chipset. You can check the hardware without disassembling the device.

    Method 1: Hidden engineering menus (USSD codes)

    Dial the following combinations on the phone keyboard (work on most devices, but may differ for Samsung, Xiaomi, Huawei):

    • 📞 ##4636## —testing menu (Testing). Here you can check:
      • 🔋 Battery status (tab Battery information).
      • 📶 Network signal and SIM card information.
      • 📊 Processor and RAM usage.
    • 📞 ##0*## — display test (a menu will appear checking colors, sensor, vibration).
    • 📞 *#06# - will show IMEI devices (if “Null” or “Unknown” is displayed, this is a sign of a faulty modem).

    Method 2: Hardware diagnostic applications

    Install one of these applications (all are free, but some have paid functions):

    • 🛠️ CPU-Z —shows detailed information about the processor, memory, sensors.
    • 🔋 AccuBattery —analyzes the battery condition (wear, temperature, charge speed).
    • 📊 AIDA64 —full report on the hardware and software (including stability tests).
    • 🔍 Phone Doctor Plus —tests all components (camera, speakers, microphone, GPS).

    Pay special attention to the following parameters:

    • 🔥 CPU temperature (in AIDA64 or CPU-Z). Normal: up to 40–50°C at idle, up to 70–80°C under load. If higher, cleaning is required. or replacing thermal paste.
    • 🔋 Battery capacity (in AccuBattery). If the actual capacity is less than 80% of the declared one, it’s time to change the battery.
    • 💾 Memory state (in AIDA64 → Storage). If there is bad blocks, the flash memory is degraded.
    ⚠️ Attention: If status is specified in AIDA64 section Battery Unknown or Not calibrated, this may indicate a malfunction of the power controller. In this case, calibrating the battery programmatically will not help - a repair is needed.

    ☑️ Checklist for checking hardware

    Done: 0 / 5

    4. Checking for viruses and malware

    Many Android crashes are associated with viruses or potentially unwanted apps (PUPs), which:

    • 🕵️ Steal data (passwords, SMS, geolocation).
    • 📱 Show ads on top of other applications.
    • 🔋 They drain the battery in the background.
    • 🚫 Block access to settings (blocker viruses).

    Standard antiviruses (such as Avast or Dr.Web) often miss new threats. Instead, use: Method 1: (free version) This is one of the few applications that detects and misses other antiviruses. After installation:

    Method 1: Malwarebytes (free version)

    This is one of the few applications that detects adware And spyware, missed by other antiviruses. After installation:

    1. Run full scan (not fast!).
    2. Remove all threats found, especially those marked PUP (Potentially Unwanted app).
    3. Restart the device.

    Method 2: Manual check via Settings → Applications

    Open the list of all installed applications and sort them by installation date. Pay attention to:

    • 📦 Applications with unclear names (for example, com.system.update or android.service.secure).
    • 🔄 apps that cannot be deleted (the "Delete" button is inactive).
    • 📥 Applications with rights administrator (check in Settings → Security → Device administrators).

    If you find suspicious software, but it cannot be removed:

    1. Remove administrator rights from it.
    2. Disable in settings (Application → Select software → Disable data-i="225">If malware blocks access to the Play Market or installation of an APK, download an antivirus (for example,Applications → Select software → Disable).
    3. If it doesn't help, delete it via ADB: 
      adb uninstall com.package.name
    How to remove a virus if it blocks the installation of an antivirus?

    If malware blocks access to the Play Market or APK installation, download an antivirus (for example, Malwarebytes) on another device, rename the file to update.apk and transfer it to your smartphone via a USB channel in file transfer mode.

    5. via PC: ADB, Fastboot and specialized utilities

    If the smartphone does not turn on or is stuck on the logo, you can diagnose it through a computer using tools ADB (Android Debug Bridge) and FastbootThis requires minimal technical skills, but allows you to identify problems that are not available through standard menus.

    Step 1: Install ADB and Drivers

    Download Platform Tools from the official Android website (link) and unpack the archive Then:

    1. Connect your smartphone to your PC in Transfer files (if it turns on) or Fastboot (if it boots only in this mode).
    2. Open the command line in the folder with platform-tools and check the connection: 
      adb devices

      If the device is detected, you can begin diagnostics.

    Step 2: Basic commands for checking

    Command What it does Example output
    adb shell dumpsys battery Shows battery status (charge level, temperature, charging technology). health: 2 (Good), temperature: 350 (35.0°C)
    adb shell dumpsys meminfo Analysis of RAM usage. MemTotal: 6GB, MemFree: 1.2GB
    adb shell dumpsys power Information on energy consumption (useful for searching for viruses). mWakeLocks: [mHoldPartial: 3h 20m]
    fastboot getvar all Displays hardware information (serial number, model, bootloader status). secure: yes, unlocked: no

    Step 3: Recovery via Fastboot

    If your smartphone does not boot, try flashing it via Fastboot (attention: this will delete all data!):

    1. Download the official firmware for your model (search on sites XDA Developers or 4PDA).
    2. Unzip the archive and run the flash script: 
      fastboot flash boot boot.img

      fastboot flash system system.img
      

      fastboot reboot

    ⚠️ Attention: Firmware via Fastboot can lead to briku (complete inoperability) of the device if the wrong software version is selected. Always check the smartphone model (fastboot getvar product) with the firmware version.
    💡

    If the command fastboot devices does not show your device, check the drivers (especially for MediaTek chipsets) or try another USB port (preferably USB 2.0).

    6. What to do if your smartphone does not turn on: emergency methods. diagnostics

    If an Android device does not respond to the power button, this does not mean that it is broken. Possible reasons:

    • 🔋 Completely discharged battery (even if the indicator showed 10-20%).
    • 🔄 Freezing at the boot stage. (bootloop).
    • 💥 Damage to the firmware after the update.
    • 🔌 Malfunction of the power controller.

    Step 1: Forced reboot

    The combination works on most smartphones:

    • 📱 Samsung: Power + Volume Down (hold for 10–15 seconds).
    • 📱 Xiaomi/Redmi: Power + Volume Up.
    • 📱 Google Pixel: Power + Volume Down (then select Restart).
    • 📱 Huawei: Power + Volume Up + Volume Down.

    Step 2: Boot into safe mode

    If the smartphone turns on, but immediately crashes or slows down, try safe mode (disables all third-party applications):

    1. Press and hold button Power.
    2. When the shutdown menu appears, press and hold “Turn off power” (on some devices - “Restart”).
    3. Confirm entering safe mode.

    If the smartphone works in safe mode stable - the problem is in one of the installed applications. Remove the last installed apps.

    Step 3: Recovering via Recovery

    If the smartphone boots into Recovery (recovery menu), you can:

    • 🔄 Do Wipe Cache Partition (cleaning cache, does not delete data).
    • 🗑️ Run Factory Reset (full reset, deletes everything).
    • 📥 Install the firmware from the SD card (if supported).

    To get into Recovery:

    • 📱 Samsung: Power + Volume Up + Bixby.
    • 📱 Xiaomi: Power + Volume Up.
    • 📱 Google Pixel: Power + Volume Down, then select Recovery Mode.
    ⚠️ Attention: If after resetting via Recovery the smartphone still does not turn on, and the logo lights up on the screen and does not go further, this is a sign of partition damage /system. In this case, only flashing via Fastboot or EDL mode (for Qualcomm).

    7 will help. When to contact the service: signs of hardware faults

    Not all problems can be solved software. If you find although If one of these symptoms occurs, the device needs to be repaired:

    • 🔥 Overheating without load (processor temperature above 60°C when idle).
    • 🔋 Swollen battery (screen or back cover is deformed).
    • 💧 Traces of oxidation on the board (after moisture).
    • 📵 Lack of network (IMEI not detected, SIM card not recognized).
    • 🖥️ Artifacts on screen (stripes, flickering, dead pixels).
    • 🔊 No sound (speakers and microphone do not work).

    The cost of repair depends on the malfunction:

    Problem Approximate cost of repair (2026) Can I do it myself?
    Replacing the battery 1 500–4 000 ₽ Yes (if you have the tools and skill).
    Re-soldering the charging connector 2 000–5 000 ₽ No (you need a soldering gun and experience).
    Display replacement 3 000–15 000 ₽ Yes (but the risk of damaging the cables).
    Board repair (after water) 5 000–20 000 ₽ No (you need an ultrasonic bath and tester).

    If you decide to repair it yourself, stick to rules:

    • 🛠️ Use plastic spatulas for disassembly, not metal screwdrivers.
    • 🔌 Disconnect the battery before working with the board (a short circuit can kill device).
    • 📸 Take a photo of the location of all cables and screws before disassembling.
    💡

    If your smartphone falls into water, do not turn it on and do not dry it with a hairdryer! Immediately remove the battery (if removable) and take it to a service center - corrosion on the board may appear in days or weeks.

    FAQ: Frequently asked questions about Android diagnostics

    🔍 How to understand that a smartphone is slowing down due to hardware, not because of the software?

    Perform a performance test in AIDA64 or AnTuTu. If the performance is 30% or more below the average for your model, the problem is in the hardware (wear, overheating). If the tests show normal results, but there are lags, the software is to blame (viruses, overloaded firmware).

    📱 Is it possible to check a smartphone for errors without root access?

    Yes, most methods (logs, ADB, engineering menus, applications like CPU-Z) work without root. Root is only needed for deep diagnostics of the system kernel or firmware modification.

    🔋 How to check battery wear if AccuBattery shows strange data?

    Use alternative methods:

    1. Enter in the engineering menu (##4636##) code .battery info.
    2. Connect via ADB and execute adb shell dumpsys battery.
    3. If the actual capacity is less than 80% of the factory capacity, it’s time to change the battery.

    🔄 What to do if the smartphone constantly reboots?

    The reasons may be different:

    • 🔋 Faulty battery — try connecting the charger (if the reboots stop, the battery is to blame).
    • 📱 Damaged firmware — reflash the device via Fastboot or Recovery.
    • 🔥 Overheating of the processor —check the temperature in AIDA64.
    • 🛠️ Hardware failure (for example, memory chip failure)—needs repair.

    📵 Why doesn’t the smartphone see the SIM card?

    Check in order:

    1. Restart the device.
    2. Try another SIM card (maybe the problem is with the operator).
    3. Clean the contacts SIM tray (use an eraser or alcohol).
    4. Check IMEI via *#06# - if it is Null, the modem is faulty.
    5. Reflash the radio modem (section modem c firmware).

    If all else fails, the modem chip is faulty modem chip (needs re-soldering).