Xiaomi Mi 9 SE, despite its age, remains a popular device due to its compact size and productive processor. However, over time, users face the need to reinstall the operating system: whether it is a transition from the Chinese version to the global version, recovery from a failed update or a desire to get a fresh version of Android. Fastboot is considered one of the most reliable and “clean” ways to restore the functionality of the device.
Unlike an over-the-air (OTA) or Recovery update, using Fastboot allows you to completely rewrite all partitions of the device’s memory, eliminating possible software conflicts of residual files. This method requires you to unlock the bootloader, which will lead to the complete removal of all data from the phone.
The process does not require root rights, but involves working with command line and specialized software from developers. Errors during the preparation stage can cause the smartphone to stop responding to commands. Careful study of each step of the instruction will help to avoid turning the device into a brick and successfully complete the software update procedure.
Tools and environment preparation required
Before you start to take action, you need to prepare the workspace and software. The basic element is the computer or laptop running the Windows operating system, because drivers and utilities for Fastboot work best in this environment. While there are analogues for Linux and macOS, for beginners, using Windows 10 or 11 will be the most secure and predictable option.
You will need an original or quality certified USB-Cheap charging cables often don't support data transmission, which leads to constant connection breaks at the most critical moment. ADB And Fastboot from the official Android Developers website, which is a set of utilities that the computer will use to give commands to the smartphone.
- 🔌 USB-Data transmission cable (preferably original).
- 💻 PC with Windows and installed drivers Qualcomm or Xiaomi.
- 📂 Up-to-date firmware image in.tgz format for Fastboot (not.zip!).
- 🔋 Charge of at least 60% for stable operation during the process.
Special attention should be paid to the choice of firmware. Files for Fastboot mode always have the extension.tgz and a name that begins with the name miui_. If you downloaded a file with the.zip extension, it is intended for installation through Recovery and is not suitable for this method. You can find current versions of the software on the official portal miui.com or proven resources like xiaomifirmwareupdater.com.
⚠️ Note: Using firmware from another model (e.g., the regular Mi 9 or Mi 9 Lite) is strictly prohibited.This will lead to irreversible damage to the hardware and the inability to turn on the device.
Unlocking the Bootloader bootloader
Xiaomi has implemented a security mechanism that prevents you from reflashing a device without official permission, called Bootloader Lock, which requires that the bootloader status be changed to Unlocked to flash a phone through Fastboot, which is not instantaneous and requires you to link your Mi Account to the device.
First, you need to turn on the developer mode. Go to Settings. → On the phone and press quickly 7-10 field-by-field "Version" MIUI». After the message “You became a developer” appears, go to the menu Additional → For developers, you need to activate the "Debugging by" item. USB» And it's called "Factory Unlocking." It's going to alert you to security risks -- we agree.
Next, you will need the Mi Unlock Tool utility. Download it from the official website, install it on your PC and log in to your Mi Account. Connect your phone as normal, click "Check" and, if correct, link the device to the account. After that, you need to reboot the phone to Fastboot mode (clambing the volume button "Down" and connecting the cable) and try to unlock through the "Unlock" button in the program.
Often, the system requires a wait of 7 to 168 hours (1 to 7 days) that is normal security procedure. Repeated attempts to unlock the device before the timer expires can reset the time meter. Once successfully unlocked, the phone will be completely cleared and the open lock icon will appear on the boot screen.
Installation of drivers and setting up ADB
If the Windows Device Manager has an unknown device with a yellow icon in the “Other Devices” or “Ports” section, the drivers are not installed. The Xiaomi Mi 9 SE most often requires Qualcomm HS-USB QDLoader 9008 drivers or standard Android Bootloader Interface.
The easiest way to install drivers is to install them automatically. The folder with loaded platform tools (ADB and Fastboot) often has an installation script, or you can use third-party packages like Xiaomi USB Driver. Once you install the drivers, check the connection: connect the phone in Fastboot mode, open the command prompt (cmd) in the tool folder and type in the command:
fastboot devicesIf you see a string with a set of numbers and letters, such as 12345678 fastboot, then the connection is successfully established and you can go to the firmware. If the window immediately closes or writes "list of devices empty", the problem is in the drivers or the driver. USB-cable.
- 🖥️ Open the Device Manager and check for unknown devices.
- 🔄 Use the original port USB 2.0 on the motherboard (back of the system unit).
- 🛠️ If you make an error, try manually updating the driver by pointing the path to the adb folder.
- ✅ Make sure the device serial number is displayed in the command line.
⚠️ Warning: If a computer makes a sound of the device connecting every few seconds, it is a sign of poor contact or faulty cable».
The process of firmware through the command line
This is the most important step. The downloaded firmware archive (.tgz) must be unpacked. Inside must be a folder containing many files and scripts. flash_all.bat. Run firmware through this script, as it contains the correct sequence of commands for all memory partitions.
Place the unpacked firmware folder in the root of the C disk (the path should not contain Cyrillic alphabets or spaces, for example). C:\miui_ROM\). Open the command line on behalf of the administrator, go to the folder with ADB-Then you put it in the firmware folder. flash_all.bat. The process will take 300 before 600 seconds.
☑️ Checklist before running the firmware
During the process, lines of code will appear in the command line window to report the progress of partition writing (sending 'system'..., writing 'system...). This process cannot be interrupted. If the script is successful, Finished. Total time: X.XXs will appear, and the phone will automatically restart. The first download can last up to 10 minutes.
There are modified scripts, for example. flash_all_except_data_storage.bat. It flashes through the system, but it doesn't touch the user data partition, and you only need to use it if you're sure that versions are compatible (e.g., switching from one global firmware to another global firmware). → Global) use only full cleaning through flash_all.bat.
Solving Typical Errors and Problems
Even if you follow the instructions strictly, you can have failures. One of the common errors is FAILED (remote: 'Flash storage is write-protected'). This means that the bootloader is locked. You have to go back to the unlock step through the Mi Unlock Tool. Another common problem is a system or vendor error.
If the phone went into a bootloop cycle after you ran it, try resetting it with Recovery. Press the "Loud Up" and "Power" buttons. In the Recovery menu (which may be in Chinese, but the buttons are standard), select Wipe Data → Wipe All Data. If that doesn't work, you may have had an incompatible version of the software stitched in.
| Mistake. | Probable cause | Method of decision |
|---|---|---|
| FAILED (remote: device is locked) | bootloader locked | Unlocking with Mi Unlock Tool |
| FAILED (data too large) | Lack of space or an incorrect script | Use it. flash_all.bat and clear the data |
| Waiting for device | No PC connection. | Check the cable, drivers and USB port |
| CRC error in unpacking | Firmware file damaged | Download the archive again, check the checksum |
What if the phone shows a black screen and vibrates?
Completion of customization and optimization
After a successful boot, you will see the welcome screen. The system will be clean, like from the store. On Xiaomi Mi 9 SE, after the first installation, it is recommended to immediately update the system components through the settings. Go to Settings → About phone and check for updates. It is also worth updating Google Play Services and all preinstalled apps.
To optimize battery life after firmware, let the phone lie on charge for about an hour when it's off or on, this is necessary to calibrate the power controller, which may have lost its way during partitioning. The first 1-2 days of battery consumption can be higher than usual - this system indexes files and optimizes databases.
💡
After the first download, disable unnecessary MIUI services (advertising, application autostart) in the Advanced Settings section to improve system performance.
Now your Xiaomi Mi 9 SE is running on the latest version of the software. Regular backup creation through Mi Cloud or Google One will help avoid data loss in the future. If you plan to experiment with firmware often, keep the unlocked bootloader, but remember to reduce the security level of banking applications in this state.
💡
Successful firmware through Fastboot guarantees a clean system without garbage, but requires strict adherence to the sequence of actions and the presence of an unlocked bootloader.