Changing the operating system on a mobile device is one of the most radical ways to breathe a second life into an outdated gadget or get advanced control options that are not available in the standard shell. Users are often looking for a way to switch from MIUI to pure Android or install a custom version for the sake of improved performance and lack of advertising. However, this process is fraught with serious risks that can lead to the smartphone being turned into a “brick.”
Before you begin any action, you must be clearly aware of what you are doing. The procedure rooting and flashing the device will void the manufacturer's official warranty. In addition, many banking applications and services with a high degree of data security may stop working on modified systems without additional complex manipulations. Weigh the pros and cons before you begin.
Device preparation and backup
Any intervention in the system memory partition carries the risk of data loss. Even if you plan to simply update your Android version via custom recovery, there is always the possibility of a failure. Therefore, the first and most critical step is to create a complete backup of all important files, contacts and settings.
Use cloud services to synchronize contacts and photos, but do not rely on them completely. It is best to create a full system image (Nandroid backup) immediately after obtaining superuser rights, if the chosen method allows it. This will allow you to roll back to the original state in case of failure.
You also need to make sure that the battery charge level is sufficient. The firmware process can take from 10 minutes to an hour, and a sudden power outage at this moment is fatal for the device. Charge your phone to at least 80%, or better yet, connect it to a power source for the duration of the entire procedure, if this is technically possible and safe.
⚠️ Attention: Make sure that the ADB and Fastboot drivers are installed correctly on your computer. Lack of communication between the PC and smartphone at a critical moment can interrupt the process of writing system files.
☑️ Checklist before flashing
Unlocking the bootloader
The bootloader is a app that runs before the operating system and verifies the integrity of the signature downloadable software. Smartphone manufacturers block it to prevent users from installing unverified systems. To change the OS, you will definitely need to unlock Bootloader.
The unlocking procedure is unique for each manufacturer. For example, devices Xiaomi require a wait of 7 to 15 days after submitting an application through the official utility. At the same time, many models allow you to do this almost instantly through commands in Fastboot mode. It is important to understand that unlocking the bootloader almost always leads to a complete reset of the device to factory settings (Wipe Data). All data will be permanently deleted the moment the unlock command is executed. Therefore, a backup must be made before starting to work with the bootloader. Google Pixel or OnePlus allow you to do this almost instantly through commands in Fastboot mode.
It is important to understand that unlocking the bootloader almost always leads to a complete reset of the device to factory settings (Wipe Data). All data will be permanently deleted the moment the unlock command is executed. Therefore, a backup must be made before working with the bootloader.
fastboot oem unlock
fastboot flashing unlock
After entering the appropriate command, a warning will appear on the phone screen. To confirm the action, you usually need to use the volume buttons to select "Unlock the bootloader" and the power button to confirm. After the reboot, you will see a warning that the device is not certified - this is normal for an unlocked gadget.
Why can’t some phones be flashed?
Some manufacturers, such as Huawei (new models) or Honor, have completely closed the possibility of receiving an unlock code. Without this code, installing custom recovery and changing the OS is technically impossible using legal methods.
Installing custom recovery (TWRP)
The standard recovery menu (Stock Recovery) has extremely limited functionality and allows you to install only official updates with a digital signature from the manufacturer. To load a third-party operating system, you need to install a custom recovery, the most popular of which is TWRP (Team Win Recovery Project).
The recovery image must be strictly adapted to your specific device model. Using an image from a similar model, even with the same processor, can lead to the sensor or camera not working or completely blocking the phone. Download files only from trusted resources, such as the official forum XDA Developers.
Installation is performed in Fastboot mode. Connect your phone to your computer and run the firmware image command. After successful recording, it is important to prevent automatic loading into the system, since the standard OS can overwrite the custom recovery back to stock at the first start.
| Action | Command / Method | Risk |
|---|---|---|
| Login Fastboot | adb reboot bootloader |
Low |
| Check status | fastboot getvar all |
Low |
| Write TWRP | fastboot flash recovery twrp.img |
Medium |
| Boot to TWRP | Volume + power buttons | Low |
Immediately after installing TWRP, go to Settings and turn on the "Keep TWRP mounted" checkbox so that the system does not replace the recovery on the first boot.
Selecting and searching for a suitable one firmware
Choosing an operating system is a creative process that depends on your goals. If you need stability and closeness to the stock experience, you should pay attention to the projects LineageOS or Pixel Experience. For enthusiasts who want maximum performance and fine-tuning, crDroid or Paranoid Android.
When searching for firmware, pay attention to the build status. Stable versions undergo long-term testing and are suitable for everyday use. Nightly builds contain the latest fixes and features, but may have critical errors, such as Bluetooth or camera malfunctions.
Be sure to read the discussion thread for the selected firmware on the forum. Often there you can find information about broken functions (bugs) that the developer has not yet fixed. For example, VoLTE or a fingerprint scanner may not work in some builds.
⚠️ Attention: Interfaces and firmware capabilities are constantly changing. A feature that worked in last month's version may be removed or broken in the new build. Always check the list of changes (Changelog) before installation.
The process of installing a new operating system
The installation process itself takes place directly in the custom recovery menu. Before flashing a new system, you must perform a complete data reset (Wipe). This includes wiping the Dalvik/ART Cache, System, Data and Cache partitions. Formatting the internal storage (Internal Storage) is usually not required if you do not change the file system.
After clearing the partitions, go to Install. Select the archive with the firmware that you previously copied to the internal memory or SD card. Confirm the action with a swipe. The process of unpacking and writing files may take several minutes.
If you are using the Google Apps package (GApps), it must be installed immediately after flashing the system, but before the first boot. Without clearing the recovery cache, install the GApps archive. Violation of this sequence can lead to constant crashes of Google services.
Once the installation is complete, click the "Reboot System" button. The first boot of a new operating system always takes much longer than usual - from 5 to 15 minutes. During this time, the animation logo may be displayed on the screen. Do not try to forcefully reboot the device if the loading indicator is active.
Violation of the installation order (System -> GApps -> Reboot) is the most common cause of a cyclic reboot (bootloop) immediately after the first installation.
Solving common problems and errors
Even if you strictly follow the instructions, problems may arise problems. One of the most common problems is "Bootloop", where the phone constantly reboots before reaching the lock screen. In this case, you need to boot into Recovery mode again and perform a full Wipe Data/Factory Reset, and then repeat the firmware installation.
Another common problem is lack of communication or broken IMEI. This often happens when the EFS or Modem partition is damaged during incorrect manipulations. Restoring these partitions is only possible if you have a prior backup made before starting any experiments.
If the touch screen does not respond on a new system, you may have installed firmware that is incompatible with your display or drivers. In this case, only returning to the stock firmware via EDL mode (for Qualcomm) or Download Mode (for Samsung) will help.
- 🔋 The phone does not turn on: Try holding down the power and volume buttons for 10-15 seconds to force a reboot or enter Fastboot.
- 📶 No network: Check if the correct modem and radio module are installed for your region and model.
- 🔒 Decryption error: When switching from an encrypted partition to an unencrypted one (or vice versa), full data formatting is required through the Wipe -> Format Data menu.
Return to factory firmware (Stock ROM)
If the experiment was unsuccessful or you decide to sell the device, you need to return everything to its original state. Each brand has its own utilities: Mi Flash Tool for Xiaomi, Odin for Samsung, SP Flash Tool for devices on MediaTek processors.
The return process is usually more complicated than installing a custom one, as it requires installing specific drivers and putting the phone into a special boot mode. Download stock firmware only from official websites of manufacturers or reputable portals to avoid malware.
After flashing the stock firmware, it is highly recommended to unlock the bootloader and lock it again if you plan to use the device for a long time. However, keep in mind that locking the bootloader on a device with a custom recovery or system will result in a brick. First, return the stock recovery!
⚠️ Attention: Locking the bootloader (Command: fastboot oem lock) is ONLY allowed if the phone has a completely stock firmware and stock recovery installed. Otherwise, the device will stop booting.
Is it possible to change Android to iOS?
No, this is technically impossible. The operating system is iOS developed exclusively for Apple devices and is closed for installation on other platforms. Processor architecture and security protections prevent iOS from running on Android smartphones. There are only design themes that imitate the iPhone interface.
Will changing the OS erase all my data?
Yes, in 99% of cases, the process of changing the operating system involves a complete reset of the device (Wipe Data). All photos, contacts and applications will be deleted. The exception is some methods of updating "over" without cleaning, but they are extremely risky and are not recommended by experts.
Will banking applications work after flashing?
By default, banking applications (Sberbank, Tinkoff, etc.) do not work on devices with an unlocked bootloader or root access for security reasons. However, using special modules (for example, Magisk Hide or Zygisk) you can hide the fact of system modification and restore the functionality of applications.
What is a “brick” and can it be revived?
“Brick” is a slang name for a phone that does not turn on and does not respond to user actions. Soft brick can be fixed by flashing it via Recovery or Fastboot. Hard brick (Hard Brick), when the phone does not show signs of life, often requires hardware repair or programming through test points on the board.