Blocking the bootloader on Xiaomi Redmi 9A: safe ways and pitfalls

The Xiaomi Redmi 9A is one of the most popular budget smartphones, but owners often face the need to manipulate the bootloader, whether it’s to return the warranty, improve security, or fix bugs after a failed firmware, locking the bootloader can be the solution, but it carries risks that most users don’t even know about.

Unlike unlocking, which is well documented on forums, locking the bootloader is a more complex and potentially dangerous operation. Mistakes can turn your Redmi 9A into a brick, and official tools from Xiaomi do not always work predictably. In this article, we will discuss all the current blocking methods, from the standard Mi Unlock Tool to manual commands via fastboot, and also explain how to avoid typical errors.

We will pay special attention to the nuances associated with the Redmi 9A (dandelion): its unique configuration of the bootloader, the limitations on the MIUI version and the peculiarities of working with Xiaomi tools.

Why you might need to lock the bootloader on Redmi 9A

At first glance, blocking the bootloader seems pointless, because unlocking opens up access to customization, but there are at least 5 good reasons to return everything "as it was":

• 🔄 Warranty returns: Xiaomi service centers refuse repairs if they detect unlocked bootloader.Blocking increases chances of free service.
• 🛡️ Increased security: Unlocked bootloader makes the device vulnerable to malicious software, especially if the phone falls into the wrong hands.
• 📦 Phone Sale.Shopping buyers in the secondary market often check the bootloader status through fastboot oem device-info and can trade or drop the deal.
• 🔧 Firmware error correction. Some custom firmware is unstable because of the unlocked bootloader.
• 📱 Recovery OTA-Xiaomi blocks updates "over the air" on devices with unlocked bootloader.

It is important to understand that locking the bootloader does not reset data on the phone, but it can lead to the loss of the ability to install custom recavators (for example, TWRP) in the future. If you plan to return to experiments with firmware, weigh the pros and cons.

⚠️ Attention: Lock the bootloader on Redmi 9A with a fixed custom firmware (not a MIUI) You can't boot the system, and you have to go back to the stock room before the procedure. MIUI!

Preparing the phone for the loader lock

An unprepared device can turn into a brick in the first stage. To avoid this, follow the following steps:

Return the stock firmware MIUI (if custom-set)|Make a backup copy of data (photos, contacts, messages)|Charge your phone at least 60%|Make sure that the PC has installed Xiaomi drivers (Mi Phone Manager)|Download the latest version of the Mi Unlock Tool from the official website-->

Pay special attention to the version MIUI. On the Redmi. 9A The locking of the loader is possible only on official assemblies (Global, EEA, If you have custom firmware installed (e.g. Pixel Experience or LineageOS), go back to the stock first via fastboot:

fastboot flash boot boot.img


fastboot flash system system.img




fastboot flash vendor vendor.img




fastboot flash dtbo dtbo.img

For Redmi 9A, it is critical to use the firmware of the same MIUI version as it was originally. For example, if the phone was bought with MIUI 12.0.8, you should not install MIUI 14, which can cause conflicts when you lock. You can check the current version in Settings → About Phone → MIUI version.

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If the phone doesn't boot after returning to stock firmware, try resetting via fastboot erase userdata.This will delete all data, but often solves the problem of hanging on the logo.

The official method: locking through the Mi Unlock Tool

The safest way is to use the official tool from Xiaomi, but it doesn't always work, especially on older versions of MIUI.

1. Link your Mi Account to your phone. Go to Settings → Xiaomi Account → Mi Cloud and make sure the device is tied.
2. Activate debugging via USB. Go to Settings → About Phone, 7 times click on MIUI Version, then go back to Settings → Additional → For Developers and enable USB Debugging.
3. Connect the phone to the PC and confirm the debugging permission.
4. Launch the Mi Unlock Tool (download from the official website), sign in to your Mi Account.
5. Transfer your phone to fastboot: adb reboot bootloader
6. In the tool, press Unlock. Despite the name, the same button is used to lock if the bootloader is already unlocked.

It takes 5-10 minutes, and when it's done, it automatically restarts, and you can check the status of the bootloader by using the command:

fastboot oem device-info

Look for the line Device unlocked: false.

⚠️ Note: If you previously blocked a bootloader on the same Mi Account, Xiaomi can block the ability to re-unblock for 30 days!

Official (Mi Unlock Tool)|Manual (via fastboot)|I don't know.|I tried it before, it didn't work.-->

Unofficial method: manual lock via fastboot

If the Mi Unlock Tool doesn't work, you can manually lock the bootloader through fastboot commands, which is a riskier method, but often saves you in desperate situations.

• 🖥️ Computer with installed ADB and Fastboot (download to Android) SDK).
• 📱 Phone with unlocked bootloader and enabled debugging USB.
• 🔌 Original. USB-cable (cheap cables can cause data transmission errors).

Instructions:

1. Connect your phone to your PC and move it to fastboot: adb reboot bootloader
2. Check the connection: fastboot devices must display the serial number of the device.
3. On Redmi 9A, this command may not work the first time – repeat it 2-3 times at intervals of 10 seconds.
4. Reboot the phone: fastboot reboot

If the fastboot flashing lock command is FAILED (remote: 'Flashing is not allowed in Lock State'), try the alternative:

fastboot oem lock

Some versions of the Redmi 9A (especially those with MIUI 13+) may require additional authentication through a Mi Account.

Typical errors and their solutions

Even with the exact instructions, Redmi 9A users are facing problems.

One of the most insidious errors is the loss of IMEI after blocking, which happens when the nvram partition is not saved before the procedure, and you can only restore the IMEI through an engineering menu or specialized utilities like Maui META, but this requires a separate instruction.

Another common problem is cyclic bootloop, and if your phone is constantly rebooting after locking, try:

1. Press Power + Volume up for 10 seconds for forced shutdown.
2. Download to fastboot and flash boot.img from stock firmware.
3. If it doesn’t work, you can reset the entire device via fastboot erase userdata.

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Before locking the bootloader on Redmi 9A, be sure to check the operability of all functions: camera, mobile network, Wi-Fi. If something worked incorrectly before the procedure, locking can aggravate the problem.

How to check the status of the bootloader after blocking

To make sure that the bootloader is successfully blocked, you can in several ways:

1. Fastboot: fastboot oem device-info Device unlocked: false Device critical unlocked: false
2. Using the phone menu: Go to Settings → About Phone. Click 7 times on the MIUI version to activate the developer menu. Go back to Settings → Additional → Developer. Check bootloader Status - should be indicated Locked.
3. Through an app (e.g. Device Info HW from Google Play). The Bootloader section will indicate the status.

If the bootloader status has not changed, repeat the lock procedure or try another method.Some versions of Redmi 9A (e.g., with MIUI 12.5 Enhanced) may require additional reboot after locking to update the status.

⚠️ Note: Some bootloader status checkers (e.g. Bootloader Checker) may show incorrect data. Trust only the output of the fastboot oem device-info command.

What to do if the lock is unsuccessful

If the Redmi 9A is not activated or is not stable after trying to lock it, don't panic. 90% of the time, the phone can be restored.

1. Try to boot up in fastboot: Press Power + Volume down for 10-15 seconds. If the Mi Bunny logo appears in the Ushanka hat, the phone is in fastboot mode.
2. Fastboot flash boot boot.img fastboot flash system.img fastboot flash vendor vendor.img Use the firmware of the same MIUI version as before the lock.
3. If fastboot doesn't respond: Try connecting your phone to another USB-port (preferably) USB Install drivers manually through Device Manager (select Android Bootloader Interface).

Extreme case - EDL mode

• Turn off the phone, press Volume up + Volume down and connect to the PC.
• The phone is called the Qualcomm HS-USB QDLoader 9008.
• Use the Mi Flash Tool for full flashing.

If the phone is not even fixed in EDL, Maybe damaged. USB-The port or the power controller, in which case only repairs at the service center will help.

FAQ: Frequent questions about locking up a bootloader on Redmi 9A