How to change the firmware on Android via a computer: a safe algorithm for beginners and advanced users

Flashing an Android device via a computer is a procedure that can radically change the operation of your smartphone: from eliminating system lags to installing custom firmware with advanced functions. However, this process requires precision and understanding of each step. Unlike updates "over the air" (OTA), manual firmware via a PC gives control over the software version, but also carries risks - from data loss to "bricking" the device.

This article is suitable for both owners Samsung Galaxy, Xiaomi Redmi or Google Pixel, and those who work with less popular brands. We will analyze not only the standard process through Odin (for Samsung) or Fastboot (for Pixel/Nexus), but also universal methods using SP Flash Tool for devices on chips MediaTek. We will pay special attention to preparation - without it, even correctly downloaded firmware may not install.

1. Preparing the device and computer: what needs to be done BEFORE flashing the firmware

The first step is backing up your data. The firmware erases the device's internal memory, including photos, contacts and messages. Use Google Account to synchronize contacts and calendar, and for other data - apps like Titanium Backup (requires root) or manual copying to a PC. Don't forget about DCIM (photo/video) and folder Downloads.

Next, check the firmware compatibility. Find out the exact model of your device in Settings → About phone → Model. For example, Redmi Note 10 Pro has modifications for different regions (sweet, sweetin). The downloaded firmware for sweet will not be suitable for sweetin —this will lead to installation errors or non-functioning modules (camera, NFC).

• 🔋 Charge your phone at least on 70% —a sudden shutdown during firmware may make the device inoperable.
• 🔌 Use the original USB cable. Cheap cables often do not transmit data stably, which leads to failures.
• 🖥️ Install drivers: for Samsung — Samsung USB Drivers, for MediaTek — MTK Drivers, for Qualcomm — QDLoader.
• 🔓 Unlock OEM Unlock v Settings → For developers. Without this, the bootloader will not allow you to install custom software.

⚠️ Attention: On some devices (for example, Xiaomi s MIUI) linking an account to the device may block the firmware. If you have forgotten your account details, unlocking the bootloader will become impossible without an official service center.

2. Choice of firmware: official vs custom

Official firmware is released by the manufacturer and guarantees stability, but often lacks new features. Custom ones (for example LineageOS, Pixel Experience) offer the latest versions of Android, but may have hardware bugs. Below is a comparison of key parameters:

Criterion	Official firmware	Custom firmware
Stability	⭐⭐⭐⭐⭐	⭐⭐⭐ (depending on builds)
Security updates	Regular (if the device is supported)	Depends on the community
Additional functions	Limited by the manufacturer	Advanced settings, themes, root
Support for banking applications	Yes (if there is no root)	May not work (due to SafetyNet)

Where to download firmware:

• 📱 Official:
  • Samsung: samfw.com or sammobile.com
  • Xiaomi: xiaomifirmwareupdater.com
  • Google Pixel: developers.google.com/android/ota
• 🛠️ Custom:
  • forum.xda-developers.com (check the build reviews!)
  • lineageos.org (for pure Android)

⚠️ Attention: Firmware from unverified sources may contain malicious code or be compiled with errors. Always check the hash sums (MD5, SHA-1) of the downloaded file with the official data.

3. This firmware is not possible

The bootloader (bootloader) is the app that starts the operating system. By default, it is locked to protect against unauthorized changes. Unlocking erases all data and may void the warranty:

• 📱 Samsung: use the Download Mode (press Volume Down + Power) and tool Odin.
• 📱 Xiaomi: requires account linking Mi and waiting 7 days after the unlock request via en.miui.com/unlock.
• 📱 Google Pixel: command fastboot flashing unlock v terminal.
• 📱 OnePlus: similar Pixel, but you may need an unlock code from the manufacturer's website.

For devices with MediaTek (many Redmi, Realme) unlocking often occurs automatically during the first firmware update via SP Flash Tool. However, some models (for example Redmi Note 8 Pro) require additional software - MTK Auth Bypass.

fastboot oem unlock
For most devices (except Xiaomi/Samsung)
After executing this command, the phone will reboot and erase all data.

⚠️ Attention: On devices c Exynos (for example, Samsung Galaxy S21 Ultra) unlocking the bootloader can trigger the hardware flag KNOX, which will forever deprive you of the ability to use Samsung Pay and some protected functions.

Make a backup copy data|Make sure the battery is charged >50%|Download official drivers for your model|Get the unlock code (for Xiaomi/OnePlus)|Connect the original USB cable-->

4. Tools for firmware: what software to use

The choice of app depends on the processor of your device:

• 🔧 Odin — for Samsung (works only with firmware in the format .tar.md5). The latest version is a universal tool for devices with processors (for devices with processors). Supports firmware in format Odin3 v3.14.4.
• 🔧 Fastboot — a universal tool for devices with Qualcomm Snapdragon (Google Pixel, OnePlus, Xiaomi with processors Snapdragon).
• 🔧 SP Flash Tool - for devices on MediaTek (Redmi Note 9, Realme 6). Supports firmware in the format scatter.txt.
• 🔧 QFil —for devices with Qualcomm with damaged firmware (requires file prog_emmc_firehose.mbn).

To work with Fastboot i ADB download platform-tools from the site Google. Unpack the archive to the root of the disk C:\ for convenience (this way the paths to the files will be shorter). Check the installation by running on the command line:

fastboot --version
It should display the version, for example: fastboot version 33.0.3-8987943

Firmware via SP Flash Tool on devices with a MediaTek Helio G95 chip (for example, Redmi Note 9 Pro) requires disabling SLA protection in the tool settings. Without this, the process will end with the error "SLA Auth Fail" (code 5054).

What to do if Odin does not see the device?

1. Reinstall the drivers Samsung USB Drivers manually through Device Manager.

2. Try another USB port (preferably USB 2.0 on the back of the PC).

3. Disable your antivirus - it may block the connection.

4. Use Odin version 3.13.1 for older models (Galaxy S7 and earlier).

5. Step-by-step guide: flashing firmware via Fastboot (using the example of Google Pixel 6)

This method is suitable for most devices on Qualcomm Snapdragon. First unlock the bootloader and download the firmware in format .zip (for example, from the site Google for Pixel).

1. Unpack the archive with the firmware into the folder with platform-tools.

2. Switch the phone to mode Fastboot: turn off the device, then press Volume Down + Power.

3. Connect the phone to the PC and check the detection:

   fastboot devices
   The serial number of the device should appear

4. Run the firmware script (for Pixel this is the file flash-all.bat):

   flash-all.bat

   For other devices use the commands manually:

   fastboot flash boot boot.img
   fastboot flash system system.img
   fastboot flash vendor vendor.img
   fastboot flash dtbo dtbo.img

5. After completion, do:

   fastboot reboot

The first startup after flashing may take up to 10 minutes - do not interrupt the process. If the device is stuck on the logo for more than 15 minutes, try resetting the cache via Recovery (Volume Up + Power).

⚠️ Attention: On some devices (for example, OnePlus 9 Pro) firmware via Fastboot requires disabling signature verification. To do this, before flashing, run:

fastboot oem disable_verity

6. Firmware via Odin (for Samsung Galaxy)

Samsung uses its own firmware protocol, so it will not work here Fastboot. You will need Odin (version 3.14.4) and firmware in format .tar.md5. Download files only from trusted sources - fake firmware may contain backdoors.

1. Run Odin as administrator.

2. Switch the phone to mode Download Mode: turn off the device, then hold down Volume Up + Volume Down, connect the USB cable.

3. A message will appear in Odin Added! with a com port (for example, COM3).

4. Click BL and select the file BL_*.tar.md5 from the firmware. Repeat for AP, CP, CSC.

   • 📌 AP — the main firmware (weighs several GB).
   • 📌 CSC — regional settings. Select HOME_CSCif you do not want to reset the data.

Uncheck the Auto Reboot (this will help avoid stuck on the logo).

Press Start and wait for the message PASS! (usually 5-10 minutes).

Turn off the device, then manually reboot it into Recovery (Volume Up + Power) and do Wipe Cache Partition.

If Odin gives an error FAIL! with code SW REV CHECK FAIL, it means the firmware version is lower than the current one. In this case, a patch is required via Magisk or searching for a newer build.

How to flash only a separate partition (for example, a modem) in Odin?

1. Upload the file only for the required partition (for example, CP_*.tar.md5 for the modem).

2. In Odin, leave a checkmark only opposite this section (the rest should be empty).

3. Click Start. This is useful if after the firmware the network or Wi-Fi signal is lost.

7. Solving common errors when flashing firmware

Even if you follow the instructions exactly, failures may occur. Below are typical errors and ways to eliminate them:

Error	Cause	Solution
fastboot: error: cannot load 'boot.img'	Incorrect file path or damaged image	Check the file extension and path (without spaces). Redownload the firmware.
Odin: NAND Write Start!! FAIL!	Incompatible firmware or damaged memory	Try a different firmware version. If the error repeats, there is a problem with the memory chip.
SP Flash Tool: S_FT_ENABLE_DRAM_FAIL (4032)	Inappropriate scatter.txt or problem with drivers	Download the correct scatter for your model. Reinstall the drivers MediaTek.
The device does not turn on after flashing the firmware	Damaged bootloader or incorrect firmware	Try flashing only boot i recovery. If it doesn’t help, take it to the service.

If after flashing the phone the phone boots in a cycle (bootloop), try:

1. Reset settings via Recovery (Wipe Data/Factory Reset).
2. Flash again, but with a checkmark Auto Reboot in Odin.
3. Install custom recovery (for example, TWRP) and flash the zip archive with firmware through it.

⚠️ Attention: If the device, after unsuccessful firmware, does not respond to buttons and is not detected by the computer, this may be a sign of chip damage. In this case, professional repairs are required using type programmers eMMC-chip. In this case, professional repairs are required using type programmers EasyJTAG.

8. After the firmware: what to do next

Successful firmware is only half the battle. Now you need to configure the system and check its functionality:

• 🔄 Data recovery: use backup copies (if you did it via Titanium Backup or Swift Backup). Do not restore system applications - this may cause conflicts.
• 🔒 Check SafetyNet: if you plan to use banking applications, check the status via SafetyNet Test in Google Play. When the trigger is triggered, install Magisk and module Universal SafetyNet Fix.
• 📡 Test hardware:
  • Camera: take photos and videos in different modes.
  • Network: check operation 4G/5G, Wi-Fi, Bluetooth.
  • Sensors: use the application Phone Tester to diagnose the gyroscope, accelerometer.
• 🔋 Battery calibration: after flashing the firmware, discharge the phone to 0% and charge to 100% without interruption. This will help the system correctly display the charge level.

If you have installed custom firmware, keep an eye out for updates via OTA (if supported) or manually on the developer forum. Some assemblies (for example Pixel Experience) are updated monthly.

FAQ: Answers to frequently asked questions

Is it possible to flash a phone without unlocking the bootloader?

No. Without unlocking the bootloader, you can only install official updates via OTA or Recovery. Any manipulations with the firmware via a PC require unlocked bootloader.

Why does Odin show "PASS!", but the phone does not turn on?

This is a typical situation when flashing firmware Samsung with a checkmark Auto Reboot. Try:

1. Disconnect the device from the PC.
2. Press Volume Down + Power for 10 seconds to force a reboot.
3. If that doesn't help, flash it again with it disabled Auto Reboot and manually reboot the phone c Recovery to reset the cache.

How to return the official firmware after custom?

The process depends on the manufacturer:

• For Samsung: download the official firmware with samfw.com and flash through Odin with file CSC (not HOME_CSC) to reset all data.
• For Google Pixel: use script flash-all.bat from the official archive.
• For Xiaomi: use Mi Flash Tool with the option Clean All.

After returning to the official firmware, the bootloader will remain unlocked. To block it back, use the command fastboot oem lock (but this may lead to failures if the firmware is unofficial).

Is it possible to flash a phone with a damaged screen?

Yes, but it is more difficult. You will need:

1. Connect your phone to the PC and make sure that it is detected in Fastboot or Download Mode.
2. Use voice control (if the screen responds to touches) or control via ADB:

adb shell input tap x y # to emulate presses
adb shell input text "hello" # for entering text

3. For Samsung with a damaged display, connecting via DeX (if the function is supported).

If the screen is completely black, but the phone turns on, try connecting it to an external monitor via USB-C to HDMI (works on some models Samsung and OnePlus).

How to check that the firmware was installed correctly?

Perform the following checks:

• Go to Settings → About phone and check the Android version and build number with the one you installed.
• Check the operation of all sensors through the app CPU-Z or Phone Tester.
• Make sure that IMEI has not been reset (dial *#06#). If zeros are displayed instead of IMEI, recovery via QCNfile is required.
• Run a benchmark (for example, Geekbench) and compare the results with the reference ones for your model.