As soon as the smartphone begins to hang endlessly on the logo, cyclically reboot or display the “System not found” error, the user has to manually install Android via Recovery or Fastboot mode in order to replace damaged or outdated firmware with a working version of the operating system.
However installing Android this is not just copying files, but a complex procedure that requires an understanding of the system architecture. Errors at any stage can lead to the device turning into a “brick,” that is, a completely non-working unit. Therefore, before starting any manipulations, you need to carefully study the compatibility of your hardware with the desired firmware version.
In this article we will look at all stages of the process: from preparing tools to final loading into a new system. We will not use complex terms without explanation, but we will not simplify critical points, since the cost of an error here is high.
Preparing the device and selecting firmware
The first step is to find the correct system image. There is no universal firmware for all phones, even if they are released by the same brand. You need to find a file created specifically for your model, taking into account the revision of the motherboard and the type of processor. Typically, such files have an extension .zip for installation via Recovery or .img for firmware via a computer.
There are many sources of firmware on the Internet, but you should only trust trusted forums and official websites of custom shell developers. By downloading an image from a dubious source, you risk receiving modified software with built-in malicious code. Always check the checksum of the downloaded file if the author has provided such data.
In addition to the system image itself, you will need specialized software to communicate with the computer. For Qualcomm processors it is often used QPST or QFIL, for MediaTek - SP Flash Tool, and for Samsung devices - Odin. The choice of tool depends solely on the hardware platform of your smartphone.
⚠️ Attention: Never try to flash your device with firmware from another model, even if they look identical. Differences in display or power controller drivers can lead to irreversible damage to the equipment.
Before downloading the firmware, find the exact model name in the phone settings (for example, SM-G950F) and check it with the name of the archive file.
Unlocking the bootloader and obtaining root access
Modern smartphones come with a locked bootloader (Bootloader). This is a security mechanism that prevents unsigned code from running. To install a custom version of Android or even the official firmware manually, this lock must be removed. The unlocking process often results in the complete removal of all user data.
Unlocking on many devices requires obtaining a special code from the manufacturer or using USB debugging. You need to activate developer mode by clicking seven times on the build number in the About phonesection. After this, an item will appear in the menu For developers, where you should enable the option USB debugging.
Next, connecting to a computer allows you to send an unlock command through the utility ADB (Android Debug Bridge). The command looks like fastboot oem unlock or fastboot flashing unlock depending on the version of android. A warning will appear on the phone screen, which you need to confirm with the volume buttons.
- 🔓 Unlocking removes the warranty from the device in most cases.
- 🧹 The process automatically performs a full data reset (Wipe Data).
- ⚙️ Some telecom operators block bootloaders at the network level, which makes unlocking impossible.
Tools for flashing firmware via computer
The most reliable way to install the system is to use a PC. This gives control over the process and the ability to interrupt it in case of a critical error, although this does not always save. To work, you will need device drivers, which are often installed along with the firmware app.
The interface of apps like SP Flash Tool or Odin may seem complicated to a beginner. The main task is to correctly specify the paths to the firmware files. Usually these are files boot.img (kernel), system.img (system), recovery.img (recovery menu) and others. Incorrect order or selection of the wrong files will result in an integrity check error.
The phone must be connected in a special mode. For MediaTek this is often the BROM mode (the phone is turned off with the volume button held down), for Qualcomm it is the EDL (Emergency Download Mode) mode, and for Samsung it is the Download mode (pressing the combination of buttons when connecting the cable). The computer should detect the device in the task manager as a COM port or a specific Android device.
☑️ Ready for firmware via PC
Installation via Recovery menu
If the bootloader is already unlocked and custom_recovery is installed on the device (for example TWRP), the process is greatly simplified and does not require a computer. You simply copy the zip archive with the firmware to the internal memory or SD card. Then the phone reboots into recovery mode using a combination of the power and volume buttons.
In the recovery menu, the first thing you need to do is wipe the partitions. This is done through item Wipe -> Advanced Wipe. You should select sections Dalvik / ART Cache, System, Data and Cache. It is important not to format the partition Internal Storageif you store the firmware file there, otherwise installation will become impossible.
After cleaning, go to the partition Install, select the downloaded archive and swipe your finger to confirm the start of the installation. The process will take from 2 to 10 minutes depending on the memory speed and system size. Upon completion, a button will appear Reboot System.
⚠️ Attention: When installing via Recovery, be sure to make a full backup of the current state (NANDroid backup) to an external memory card. This is the only insurance in case the new system does not start.
Often, add-on packages are installed along with the system, for example Google Apps (GApps), if they are not in the firmware. They must be installed immediately after the main firmware, without rebooting the phone, following the same procedure for selecting a zip file.
Possible errors and recovery methods
Even if you strictly follow the instructions, failures may occur. The most common problem is the “bootlap”, when the phone endlessly reboots at the logo. This means a kernel-system conflict or data partition corruption. The solution is to enter Recovery again and perform a full reset (Format Data).
Another common error is “Error 7” during installation. It says that the installation script checks the device model and finds no matches. This is protection against installing incorrect firmware. It is not recommended to forcibly bypass it, as this is a direct path to failure.
If the phone stops responding to buttons and is not detected by the computer, the bootloader may be damaged. In this case, only flashing in EDL or BROM mode using authorized accounts (for some brands) or special repair boxes will help.
| Error type | Symptoms | Probable cause | Solution |
|---|---|---|---|
| Bootloop | Eternal reboot to logo | Kernel incompatibility | Wipe Data / Flash boot.img |
| Error 7 | Installation interruption in Recovery | Wrong model in updater-script | Searching for the correct firmware |
| No Command | Robot with an exclamation mark | Failure to enter Recovery | Hold Power + Vol Up |
| Black Screen | Black screen, there is vibration | Damage to the System partition | Full flashing via PC |
What is Hard Brick?
This is a state when the phone shows no signs of life: the screen is black, there is no vibration, the computer does not make a connection sound. Usually it can only be treated with a programmer or short-circuiting the contacts on the board (Test Point).
Initial setup and optimization
After successful installation and the first boot, you will be greeted by an initial setup wizard. At this stage, it is important to take your time and carefully read the data synchronization proposals. If you're restoring your phone after a crash, it's best to set it up as new to avoid carrying over old software bugs.
Immediately after downloading, it is recommended to go to the developer settings and check the animation. Sometimes custom firmware has specific energy saving settings that should be adjusted to suit your usage scenario. It is also worth checking the operation of sensors and communication modules.
To extend the life of the battery after flashing, it is useful to let the system “warm up”. This means that in the first couple of days you should not load the phone with heavy games, allowing background processes to optimize the cache and contact database.
The first boot after flashing can last up to 15-20 minutes. Do not try to force reboot your phone if you see a boot animation - this is a normal system initialization process.
⚠️ Attention: The Recovery menu and settings interfaces may differ depending on the Android version and shell type. Always check the documentation for the specific firmware version you are installing.
Do not forget that the security of the device is now entirely in your hands. Custom firmware may not receive security updates as regularly as official ones. Regularly check for security patches for your version of the system.
Is it possible to install Android on a phone for which there are no firmwares?
Theoretically, you can try to port the firmware from a similar device (same hardware platform), but this requires deep knowledge in kernel compilation and editing drivers. For an ordinary user, this is practically impossible and extremely risky.
Will the firmware erase all my photos and contacts?
Yes, in 99% of cases, the process of installing a new system requires a complete wipe of the data section (Data Wipe). Be sure to back up all important files to your computer or to the cloud before starting work.
What to do if the camera does not work after flashing the firmware?
This is a common problem when installing custom firmware. Camera drivers are kernel and system specific. Try to find and install a compatible package Camera HAL or return to the previous firmware version where the camera worked correctly.
Is it dangerous to unlock the bootloader?
Unlocking itself is safe for the hardware, but it makes the device vulnerable to malware that can access low levels systems. In addition, some applications (banking, payment) may refuse to work on an unlocked device.