How to block the bootloader on Xiaomi Mi 9 SE: all the ways 2026

Locking the bootloader on the Xiaomi Mi 9 SE is a reverse-unlock procedure that may be needed to improve device security, restore warranty or fix bugs after failed firmware experiments. Unlike most smartphones, where the bootloader locks automatically when reset to factory settings, Xiaomi devices require manual intervention, due to the company's policy to protect user data and prevent unauthorized access to system partitions.

The process of locking the bootloader on Mi 9 SE (codename grus) has its nuances: for example, the official method through Mi Unlock Tool does not work on all versions of the firmware, and alternative methods require knowledge of fastboot commands. In this article, we will discuss all current methods of 2026, including device preparation, step-by-step instructions and solutions to typical errors.

If you have previously unlocked a bootloader for installation TWRP or custom ROM, remember: locking will return the device to a drain state, but can lead to a breeze if you do not act correctly. Therefore, before starting the procedure, we recommend that you read the section FAQ, which discusses frequent questions and critical points.

1. Preparation of Xiaomi Mi 9 SE for the bootloader lock

Before locking the boot loader, several mandatory steps must be taken to avoid data loss or turning the smartphone into a "brick." The Mi 9 SE is sensitive to changes in the boot section, so preparation must be careful.

First, back up all the data, locking the bootloader will cause the device to reset to factory settings, and if you use custom firmware, there's a high risk of losing access to internal memory.

• 📱 Mi Cloud – sync contacts, notes, and photos (but not system settings!)
• 💾 Local copying on PC through MTP or ADB pull.
• 🔄 Titanium Backup (routed device only) – saves applications and their data.

Second, check the current bootloader status, turn off your smartphone, press Power + Volume Down, and go to fastboot mode, plug the device into your PC and type in the command:

fastboot oem device-info

In the conclusion, find the lines Device unlocked: true and Device critical unlocked: true. If both have the value of true, the bootloader is unlocked and you can block it.

⚠️ Warning: If you use a custom core or modified boot.img, locking the bootloader without returning to the stock firmware will result in a permanent blink. In this case, first, flash the official fastboot-ROM for Mi 9 SE.

Also make sure that the PC is installed:

• 🖥️ ADB Fastboot (part of Google’s Platform Tools).
• 🔌 Xiaomi Drivers (download from the official website or via the Mi Flash Tool).
• 📦 Official firmware for Mi 9 SE (the version must match the current or be newer).

2.Official method: lock via Mi Unlock Tool

The most reliable way to block a bootloader is to use Xiaomi's Mi Unlock Tool, but this only works on stock firmware without modifications. If you use custom ROM, go back to the official software first.

Instructions are Step-by-step:

1. Download the Mi Unlock Tool from the official website (the version should be up-to-date, for example, 6.5.224.24 or later).
2. Sign in to the Mi-account that is tied to the device (this is important!).
3. Connect the Mi 9 SE in fastboot mode (as described above).
4. Run the utility and wait for the program to determine the device.
5. Click Lock (in some versions, the button may be called "Bind Account & Lock").

The locking process will take 10 to 30 seconds, and once successfully completed, the device will automatically restart and reset to factory settings.

⚠️ Warning: If the Mi Unlock Tool gives an error This device is locked by another Mi Account, then the device was previously linked to another account, in which case you need to unlock through the Xiaomi service center with confirmation of purchase.

Once you lock the bootloader, check its status again with the command fastboot oem device-info. Device unlocked: false will confirm success.

Download the latest version of the Mi Unlock Tool|Sign in to Mi-account on phone and PC|Transfer the device to fastboot mode|Connect the original USB-cable|Disable the antivirus (can block the utility)-->

3. Alternative method: locking through fastboot commands

If the Mi Unlock Tool doesn’t work (for example, due to a Couldn’t verify device error), you can lock the bootloader manually via fastboot.This method is more risky, since it does not check firmware compatibility, but is suitable for advanced users.

Step-by-step:

1. Transform the Mi 9 SE to fastboot (Power + Volume Down) mode.
2. Connect to your PC and check for device detection: fastboot devices must display a serial number.
3. Run the lock command: fastboot flashing lock or for older versions: fastboot oem lock
4. Confirm the action on the smartphone screen (if a request appears).

Once the command is executed, the device restarts and performs a complete reset, and if the process ends with the FAILED error (remote: 'Flashing is not allowed in Lock State'), then:

• 🔧 The device has an unofficial firmware installed.
• 🔄 Stock boot.img Requires to be returned.
• 📥 You need to flash a full fastboot-ROM before you lock it.

If you block the bootloader on a device with Magisk or TWRP installed, pre-return the stock recovery and remove the root rights. Otherwise, the phone will stop booting and you will need firmware through EDL- mode.

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Locking through fastboot is only for stock firmware. On custom ROMs, this method will lead to a blink!

4.How to return stock firmware before locking

If your Mi 9 SE has custom firmware installed (such as LineageOS or Pixel Experience), locking the bootloader without returning to the sewage software will result in a loss of performance. To avoid this, run the official fastboot-ROM for your model.

Download the firmware from one of the verified sources:

• 🌐 Xiaomi official website (miuidownload) – select Mi 9 SE (grus) and the latest stable version.
• 🔗 4PDA or XDA-Developers — look for themes from fastboot-ROM for grus.

The firmware through the Mi Flash Tool:

1. Unpack the downloaded archive with firmware in a folder without Cyrillic symbols.
2. Install the Mi Flash Tool (version 2020.3.14.0 or later).
3. Put the Mi 9 SE into fastboot mode and connect to the PC.
4. In the Mi Flash Tool, select the firmware folder and click Refresh → Flash.
5. Select the clean all mode and wait until it is completed.

Once the firmware is installed, the device will automatically restart, and you can now safely lock the bootloader with any of the methods described above.

⚠️ Warning: If the Mi 9 SE is not turned on or got stuck on the Mi logo after the firmware is installed, turn the device into EDL (emergency firmware) mode using a test point or Deep Flash Cable box.

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Before you run your firmware, check the firmware version on Xiaomi. For the Mi 9 SE, current versions start with V12.5.1.0 (Android 11) or later. Installing old firmware can cause problems with the communication module or camera.

5. Common mistakes and their solutions

When blocking the bootloader on Xiaomi Mi 9 SE, users often encounter errors related to firmware incompatibility, account or driver problems.

Error 1: Couldn't verify device in Mi Unlock Tool

• 🔹 Make sure that the same Mi-account is used on the device and in the utility.
• 🔹 Re-link your account: Go to Settings → Xiaomi Account → Sign out, then log in again.
• 🔹 Check to see if your account is blocked (for example, due to suspicious activity).

Error 2: FAILED (remote: 'Device is locked by another account')

This error means that the device is linked to another account (for example, if the phone was bought with hands).

• 📞 Contact the previous owner to remove the device from your account.
• 📄 Provide proof of purchase to Xiaomi Service Center for unlocking.
• 🔧 Use EDL- mode to completely flash (requires an authorized developer account).

Error 3: The device does not turn on after locking

If the Mi 9 SE is stuck on the logo or does not respond to buttons, the reason is incompatibility of the firmware.

1. Transfer the device to fastboot (Power + Volume Down).
2. Download boot.img: fastboot flash boot.img
3. If it doesn’t work, run the full firmware through the Mi Flash Tool in clean all mode.

6. Checking the status of the loader after blocking

Once the bootloader is locked, you need to make sure that the procedure is successful, and this can be done in several ways to avoid unpleasant surprises in the future.

Method 1: Through fastboot

Connect the Mi 9 SE to your PC in fastboot mode and execute the command:

fastboot oem device-info

The conclusion should contain the following lines:

Device unlocked: false


Device critical unlocked: false

Method 2: Through Android Settings

1. Go to Settings → About Phone → MIUI version.
2. Tap 7 times on the MIUI version line to activate Developer Mode.
3. Back to Settings → Additionally. → For developers.
4. Find the item Status of the bootloader - should be indicated Blocked.

Method 3: Checking through ADB

If the device is enabled, connect it to a PC with USB debugging enabled and do:

adb shell getprop ro.boot.verifiedbootstate

Expected output: orange (unlocked) → green (locked).

⚠️ Warning: If you notice problems with Google Pay or banking applications after you lock the bootloader, this is due to a change in the status of verifiedbootstate. To restore functionality, you may need to re-unblock and firmware Magisk with the Universal SafetyNet Fix module.

FAQ: Frequent questions about locking the Mi 9 SE bootloader