Flashing a smartphone is a process that can bring a “brick” back to life, speed up the operation of an outdated device, or provide access to functions blocked by the manufacturer. Many users are afraid of this procedure, considering it to be the domain of only professional service centers, but with proper preparation and care installation of a new operating system you can do it yourself. A deep understanding of the Android architecture and strict adherence to action algorithms help minimize the risks of data loss or hardware failure.
In this article we will analyze all the stages: from unlocking the bootloader to the final setup of custom recovery. You will learn how the official firmware differs from the modified one, what tools are needed to work with a PC and how to properly prepare the device. It is important to understandthat any modification of the software carries certain risks, so responsibility for the result lies solely with the user.
The preparatory stage and the choice of software
Before you begin any actions with the system memory partition, you must make thorough preparations. The first step is to create a complete backup of all important data, as the flashing process will completely clear the internal memory. Use cloud services or connect your smartphone to your computer in file transfer mode to save photos, contacts and documents.
Choosing the correct firmware version is critical. There are two main types of software: stock (official from the manufacturer) and custom (developed by enthusiasts, for example LineageOS or Pixel Experience). Stock firmware guarantees the stable operation of all hardware modules, while custom firmware offers advanced functionality and more recent versions of Android for older models.
To work, you will need specialized software on your computer. The choice of app depends on the processor of your device:
- 📱 For processors Qualcomm the QFIL or Odin utility (for Samsung) is most often used.
- 🔧 For chips MediaTek the standard is the SP Flash Tool app.
- 💻 A universal tool for advanced users is a set of platform tools
ADBiFastboot. - 📦 You also need to download drivers specifically for your smartphone model so that the PC correctly recognizes the device in download mode.
⚠️ Attention: Download firmware and drivers only from official websites of manufacturers or trusted forums (for example, w3bsit3-dns.com or XDA Developers). Using files from unverified sources can lead to infection of the system with malware or irreversible damage to the phone.
Make sure that the battery is charged at least 60-70%. Interruption of the firmware process due to low battery is one of the most common reasons for a smartphone turning into an unrecoverable “brick.” Also prepare a high-quality USB cable, preferably an original one, since cheap analogs may not provide stable data transfer.
Unlocking the bootloader
A bootloader is a app that runs before the operating system and verifies the digital signature of the loaded software. By default, on most smartphones it is blocked by the manufacturer, which does not allow the installation of unofficial system images. The unlocking procedure (Unlock Bootloader) is a mandatory first step for any custom flashing.
The unlocking process varies depending on the brand. Devices Xiaomi require special permission through the official Mi Unlock utility and wait from 3 to 168 hours. Devices Google Pixel or OnePlus allow you to do this faster through a command in Fastboot mode. On smartphones Samsung unlocking is often carried out through a combination of buttons in Download Mode and confirming the action with the volume buttons.
Remember that unlocking the bootloader almost always leads to a complete reset of the device data (Wipe Data). In addition, on many modern smartphones, after this procedure, functions related to high security, such as Google Pay (now Google Wallet) or Widevine L1 content protection, stop working, which reduces the quality of video playback in streaming services.
To unlock via a computer, use the command line. Connect the phone in Fastboot mode (usually holding down the volume down button when turning it on) and enter the command:
fastboot oem unlockOr, for new devices:
fastboot flashing unlockA data loss warning will appear on the smartphone screen. Confirm the action using the volume buttons. After the reboot, the bootloader will be unlocked and you can proceed to the next step.
Installing custom recovery (TWRP)
The standard recovery menu (Stock Recovery) has extremely limited functionality and only allows you to reset settings or install updates from the manufacturer. To install third-party firmware, you need to replace it with a custom recovery, the most popular of which is TWRP (Team Win Recovery Project).
The recovery file image (.img) must be downloaded strictly for your specific device model. Installation is performed through Fastboot mode using the command:
fastboot flash recovery twrp_image_name.imgImmediately after executing this command, you cannot reboot the system in the usual way, since the stock system can automatically replace the custom recovery back to the factory one. You must immediately hold down a combination of buttons (usually Volume Up + Power) to enter the newly installed TWRP.
If after installing TWRP the phone boots into a regular system, try the command "fastboot boot twrp_image_name.img" to temporarily boot, and from within recovery, perform a permanent installation.
In the TWRP menu you will see a touch interface with many options. First of all, it is recommended to go to the settings (Settings) and disable signature verification (Disable dm-verity) and forced encryption if you plan to get root access. This will prevent boot problems after modifying the system partition.
| TWRP function | Description | What is it used for |
|---|---|---|
| Install | Installing ZIP archives | OS firmware, patches, Magisk modules |
| Wipe | Cleaning partitions | Full reset (Format Data) before installation |
| Backup | Creating a backup | Saving the current working system (Nandroid) |
| Restore | Recovery | Rollback to a saved copy in case of failures |
The process of installing firmware and clearing data
The most crucial moment is the direct installation of a new operating system. Firmware file (usually in the format .zip) must be copied to the phone’s internal memory or SD card. If you install custom firmware over the stock one, a complete data wipe is required.
In the TWRP menu, select Wipe, then Advanced Wipe. Check the boxes Dalvik / ART Cache, System, Data and Cache. Do not touch the partition Internal Storageif there is a firmware file on it. Swipe to confirm cleaning. This process is called “Clean Flash” and guarantees that there are no conflicts between old and new system files.
☑️ Checklist before flashing
Next return to the main menu and select Install. Find the archive with the firmware and confirm the installation by swiping. The process may take from 2 to 10 minutes depending on the memory speed and data volume. Do not interrupt the process or disconnect the cable until the progress bar reaches 100% and a success message appears.
If you are moving from one version of Android to another with a radically different base (for example, from Android 10 to Android 13), sometimes it is necessary to format the data partition into a file system format. In the Wipe menu, select the button Format Data and enter the word yes. This will delete all data, including internal memory, but is necessary for encryption to work correctly in new versions of the OS.
Installing additional components and GApps
Most custom firmware is distributed without pre-installed Google services (GApps) due to licensing restrictions. This means that after the first download you will not find Play Market, YouTube or Gmail on your phone. To get them back, you need to install the GApps package immediately after flashing the OS firmware, but before the system boots for the first time.
Download the appropriate package from the website OpenGApps or NikGApps. It is important to select the correct processor architecture (usually arm64) and the version of Android that matches the installed firmware. In the TWRP menu, select Install again and specify the downloaded GApps archive. Installation of services must be done “blindly”, that is, without a reboot between installing the firmware and services.
⚠️ Attention: The interfaces and capabilities of Google services may change with updates. Always check the compatibility of the GApps package with the specific version of your firmware on the developer forum to avoid cyclic reboots.
For users who want to gain superuser rights, the next step is installation Magisk. This tool allows you to gain root access and hide it from banking applications. The process is similar: download the Magisk APK file, rename the extension to .zip and install via TWRP.
What is a “Clean Installation” (Clean Flash)?
Clean installation involves completely formatting the data partition before flashing the firmware. This is mandatory when changing a major version of Android or switching between different types of firmware (from stock to custom). Ignoring this step often leads to a “bootlap” (infinite reboot).
First boot and eliminating possible errors
After installing all the necessary components, select the item in the TWRP menu Reboot → System. The first boot after flashing always takes much longer than usual - from 5 to 15 minutes. This is because the system optimizes applications and creates a cache. Don't panic if the logo is frozen on the screen.
If the phone is still stuck in a bootloop, return to Recovery mode. Try again Wipe Data/Factory Reset and clear the Dalvik cache. Often the problem is caused by incompatible Magisk modules or an incorrectly selected GApps package. As a last resort, you will have to repeat the firmware procedure from the very beginning, downloading the image again.
Successful loading of the desktop means that the flashing was successful. Now you have a device with clean software, free of unnecessary manufacturer garbage. However, remember that the warranty for the device after unlocking the bootloader and modifying the software is usually void.
Successful flashing requires a strict sequence: Unlock → TWRP → Wipe → Firmware → GApps → Reboot. Violation of the order of steps is the main cause of errors.
Is it possible to reflash a phone if it does not turn on?
If the phone does not turn on at all (black screen, no response to buttons), but is detected by the computer in EDL mode (for Qualcomm) or Download Mode (for Samsung), then it is possible to reflash it. For this, special emergency recovery modes and appropriate software (QFIL, Odin) are used.
Will IMEI be erased after flashing?
When flashing correctly via Recovery (TWRP), the partition with IMEI (EFS/NVRAM) is not affected and the number is saved. However, when using some tools for direct image recording (especially Chinese utilities for MediaTek), there is a risk of losing the IMEI if you do not back it up in advance.
How to return to the official firmware?
To return to stock, you need to download the official firmware image for your model. This is usually done through the Fastboot mode using commands fastboot flash system system.img and others, or using proprietary utilities like Mi Flash Tool or Samsung Smart Switch, which automatically restore the factory state.
Is it safe to use banking applications on a flashed phone?
By default, banking applications do not work on unlocked devices bootloader or root access. However, the use of MagiskHide modules (or its analogues in new versions of Magisk) allows you to hide the fact of system modification, which in most cases restores the functionality of banking software.