Blocking the bootloader on Xiaomi Redmi 9: why it is necessary and how to do it correctly

Locking the bootloader on Xiaomi smartphones is a procedure that raises a lot of questions even among experienced users. On the one hand, it returns the device to factory protection, on the other hand, it can lead to a “brick” if you do something wrong. Redmi 9 (codenamed lancelot) is no exception: its bootloader is blocked according to the same principles as other models of the line, but taking into account the features of the MIUI firmware and the hardware version.

Many people mistakenly believe that locking the bootloader is only necessary to return the warranty or sell the phone, in fact, it is used to protect against unauthorized access (for example, if the phone is stolen), to restore regular operation of the Mi Account, and even to solve problems with updates “over the air”, but the process is irreversible without official permission of Xiaomi – after blocking, you can unlock the bootloader only after 720 hours of waiting (30 days), as in the first unlock.

In this article, we will discuss all the ways to lock a bootloader on Redmi 9, from the official method through the Mi Unlock Tool to alternative solutions using fastboot. Also discuss why sometimes the lock fails, how to avoid errors and what to do if the phone stopped loading. If you have never worked with Xiaomi bootloaders, read the warnings carefully and follow the steps.

Why block the bootloader on Xiaomi Redmi 9?

At first glance, locking the bootloader seems pointless, because unlocking it gives you freedom to customize, install custom firmware and root rights, but there are several good reasons to return factory protection:

🔹 Warranty recovery: If you unlocked the bootloader for experiments but now want to give the phone to the service under warranty, locking can be a must. Xiaomi officially refuses to repair devices with the unlocked bootloader, even if the breakage is not related to the firmware.

🔹 Data security: Unlocked bootloader allows you to bypass Mi Account protection, making it easier to steal data or hack into a device, locking it back to the level of protection out of the box».

🔹 Stability: Some custom firmware or modifications may conflict with Redmi 9 hardware, causing overheating, fast battery drain, or spontaneous reboots. Locking the bootloader and returning to stock MIUI Often solves these problems.

🔹 Updates by air» (OTA). On devices with unlocked update bootloader via Settings → The system may not be installed or may not work properly.

⚠️ Attention: Locking the bootloader will not reset the phone, but it can crash if the firmware is modified. → Additionally. → Backup and reset.

Preparing for the lock: what to do in advance

Before you start blocking, make sure your Redmi 9 meets the following requirements:

• 📱 Version. MIUI: The device must work on the official firmware MIUI (global, Chinese or EEA). Custom builds (such as LineageOS or Pixel Experience) can block the process.
• 🔋 Battery charge: At least 60%. Locking through fastboot can take up to 10-15 minutes, and discharging in the process will lead to failure.
• 🖥️ Windows PC: Mi Unlock Tool officially supports only Windows 7/10/11. On macOS or Linux, you will need to use alternative methods (see section below).
• 🔌 Original. USB-Cable: Cheap cables may not transmit data in fastboot mode, which will lead to errors.

Also check the status of the loader:

1. Turn off the phone.
2. Press the Power button + Volume down to log into fastboot.
3. Connect the device to the PC and type in the command line: fastboot oem device-info
4. If the answer is Device unlocked: true, the bootloader is unlocked and ready to lock.

⚠️ Note: If Device unlocked: false in the answer, but you are sure that you have unlocked the bootloader before, it is possible that the phone has a firmware with a “fake” lock status. 0x80070057.

Make sure the firmware is official (MIUI)

Charge your phone to 60% or more

Install Xiaomi drivers on PC

Download the latest version of the Mi Unlock Tool

Create a backup copy of the data-->

The official method: lock through Mi Unlock Tool

The most reliable method is to use Xiaomi's official Mi Unlock Tool, which works even on the latest versions of MIUI and minimizes the risk of errors.

1. Download the utility from the official website en.miui.com/unlock (version must be at least 5.5.224.24 for Redmi 9).

Install the drivers:

Connect your phone in fastboot mode (see previous section).

In Device Manager, find Android Bootloader Interface and update the driver manually by specifying the folder with drivers from the Mi Unlock Tool archive.

3. log in to Mi Account:

Launch the Mi Unlock Tool and log in to the Xiaomi account that was tied to the phone before unlocking the bootloader.

If your account is not tied or you have dropped it, you will not be able to block it without a 30-day wait.

4. Connect the phone in fastboot mode and press Unlock (despite the name, the utility blocks the bootloader in the same way).

5. Wait until it's done. It takes 5-10 minutes. When it's done, the phone automatically restarts.

⚠️ Note: If the utility is unable to unlock or 0x80070057, signifier:

• The Mi Account is not linked to the phone.
• The firmware has been modified (e.g., anti-rollback removed).
• Xiaomi servers are temporarily unavailable (try it later).

Alternative method: blocking through fastboot commands

If the Mi Unlock Tool doesn't work, you can lock the bootloader manually through fastboot. This is a riskier method, but sometimes it's the only one available.

• 💻 Computer with installed ADB Fastboot (you can download it in Android) SDK).
• 📄 File. anti_rollback.db for your version MIUI (You can get it from the official firmware).

Instructions:

1. Transfer your phone to fastboot (Power + Volume Down).
2. Connect to your PC and check the connection with the command: fastboot devices (should display the serial number of the device).
3. Lock the lock: fastboot oem lock
4. If FAILED (remote: oem lock is not allowed) occurs, reset the settings first: fastboot erase userdata fastboot erase cache Then repeat the lock command.

⚠️ Note: After the command fastboot oem lock, the phone may not turn on if the firmware has been modified. MIUI via Mi Flash Tool in mode EDL.

💡

If you lock your phone on the MI logo, try pressing Power + Volume up for 10-15 seconds to force it to restart. If that doesn't work, run the phone in EDL mode.

Frequent mistakes and their solutions

Locking the bootloader on Redmi 9 is often accompanied by errors. Let's consider the most common ways to fix them:

If none of the methods worked, check:

• 🔍 Firmware Version: Redmi 9 should be installed MIUI 12.5+ (Previous versions may not support blocking).
• 🔧 Condition of connector USB: Physical damage may interrupt the transmission of data.
• 🌍 Firmware region: Chinese versions MIUI Sometimes the bootloader is blocked only through the Chinese version of the Mi Unlock Tool.

💡

If the bootloader lock is in error, don’t repeat the procedure right away — wait at least 24 hours. Frequent attempts can lead to hardware locking of the eMMC chip.

What if the phone doesn’t turn on after locking?

If Redmi 9 is not responsive to buttons or is stuck on the MI logo, don't panic. 90% of the time, the device can be restored.

Forced reset:

- Press Power + Volume up for 20-30 seconds.

If the phone vibrates, release the buttons and wait for the load.

2. Entrance to Recovery:

- Press Power + Volume up until the MIUI Recovery menu appears.

Select Wipe Data → Wipe All Data (this will delete all data, but can return to work).

3. Firmware through Fastboot:

Download the official firmware for Redmi 9 (for example, from here).

Unpack the archive and run the firmware with the command:

fastboot flash all [name file].tgz

4. Firmware via EDL (if fastboot doesn't work):

You will need a Xiaomi Authorized Account box or a paid account for the Mi Flash Tool.

Connect your phone in EDL mode (close the test points on the board or use the adb reboot edl command if adb works).

- Sweat through the Mi Flash Tool with the choice of clean all option.

⚠️ If the phone is not even identified in EDL, The preloader may have been damaged, and then only flashing through the bootloader will help. ISP (soldering equipment required).

Locking a bootloader without a computer: myth or reality?

Many users are looking for a way to lock the bootloader right from their phone, without connecting to a PC. Unfortunately, this is not possible on Redmi 9. All methods that offer “lock through settings” or “special applications” are either fraud or only work on older Xiaomi models (such as the Redmi Note 3).

The only “semi-official” way to do this without a PC is to use Xiaomi service centers, which can block the bootloader through internal tools, but:

• 💰 Service paid (from 1000 to 3000 rubles).
• ⏳ The class can take up to 5 working days.
• 📄 You will need a check or a warranty card (otherwise you will be refused).

If you urgently need to lock the bootloader, and the computer is not at hand, try to borrow a PC from friends or use public computers (for example, in the library or co-working).

FAQ: Answers to Frequent Questions