How to block the bootloader on Xiaomi: the complete guide

Owners of Xiaomi and Redmi smartphones often face the need to modify the system, but sometimes the opposite situation arises: you need to return the device to the original state of complete security. A request for how to block a bootloader on Xiaomi becomes relevant when selling a gadget, transferring it to another user or wanting to protect personal data from unauthorized access. Open Bootloader is a potential vulnerability through which an attacker can gain deep access to the file system.

The process of closing the bootloader is not trivial and requires understanding the architecture of Android on devices of this brand. Unlike installing custom firmware, the reverse process is often ignored in official manuals, which gives rise to many myths. You need to be clearly aware of the difference between flashing the stock version of the OS and physically locking the bootloader, since these actions have different consequences for warranty and functionality.

In this article, we will discuss the technical aspects of closing Bootloader, the official methods and possible risks. We will not use questionable utilities, but focus on proven ways to return the smartphone to factory status. Remember that any manipulation of low-level partitions requires careful and accurate follow-up.

What is a bootloader and why block it

The bootloader, or Bootloader, is a special program that starts before the Android operating system boots. It checks the integrity of the system partitions and decides which OS to run. Xiaomi devices have a locked bootloader installed by default, which provides a high level of security, but limits the possibility of modification. Unlocking allows you to install customized backups, obtain root rights and change firmware, but removes software protections.

Locking the bootloader returns the device to a store-like state, which is critical to some banking and contactless payment applications that may not function on modified devices, and the closed Bootloader prevents unofficial or corrupted system images from loading, which is an important barrier to viruses and malware.

⚠️ Warning: The process of locking the bootloader will result in the complete removal of all data from the device. be sure to back up important files, contacts and photos before starting any action.

There are several reasons why users are seeking to shut down the bootloader, often due to corporate security requirements or a desire to increase the liquidity of the device in the secondary market. Consumers of used equipment are wary of phones with an unlocked bootloader, as this may indicate previous software problems or interference with the system.

Preparation of the device for the locking procedure

Before you start locking, you need to make sure that the device is fully ready for the procedure. The first step is to install the official global or Chinese firmware corresponding to the region of the device. Using custom MIUI builds or ports from other devices is unacceptable, as the key signatures will not match, which can lead to a brick of the smartphone.

You will need quality. USB-cable and computer with Windows operating system. ADB Check the battery power: it must be at least 60% so that the device does not turn off at the critical moment of data recording in memory.

Special attention should be paid to the Mi Account. The device must be unconnected from the Mi Cloud account, and the Find Device function is disabled. If this is not done, after blocking the bootloader, the phone may request a password from the previous account, and it will be impossible to unlock it without a purchase check.

• 📱 Make sure the latest stable version is installed on your smartphone. MIUI.
• 💾 Save all important data to an external medium or to the cloud.
• 🔌 Use the original cable to connect to your PC.
• 🔋 Check the port’s performance USB computer-based.

The official method is Mi Unlock Tool

The most secure and recommended way to block is to use the official Mi Unlock Tool, which is developed by the manufacturer and ensures the correct operation of all security mechanisms. To get started, you need to download the latest version of the program from the official MIUI website and install it on your computer.

Once you start the utility, you need to log in using the same Mi Account that was attached to the smartphone. Then turn the phone into Fastboot mode, holding the power and volume buttons at the same time. Connect the device to the computer and wait for the program to recognize the phone.

In the program interface, select the settings menu, usually represented by a gear icon or three dots, and it should have the option "Lock Bootloader" or "Block bootloader." Pressing this button initiates the process of checking and blocking afterwards, and the system will warn you that all data will be deleted.

It takes a few minutes. You can't turn off the cable or interrupt the program. Once it's done, the phone automatically restarts and starts the factory reset procedure. The first run can take longer than usual, as the system will re-initialize the partitions.

• 🔓 Run the Mi Unlock Tool on your computer.
• 📲 Transfer the smartphone to Fastboot mode.
• 🔗 Connect the device and wait for the connection.
• 🔒 Click the lock button in the utility menu.

Blocking through Fastboot commands

For more experienced users, a command line locking method is available, which requires a minimalist set of tools, but carries an increased risk of error when typing commands. You'll need a platform-tools folder containing adb and fastboot executables.

Open the command line in the tool folder and type in the command to check the connection: fastboot devices. If you see the serial number of the device in response, then the connection is established correctly. Next, you enter the command fastboot oem lock or fastboot flashing lock, depending on the version of Android and the type of bootloader.

fastboot flashing lock

Once you have a command, you will be warned on your smartphone screen that the device will be locked and the data cleared. To confirm the action, you usually need to press the volume button or use a touchscreen if the Fastboot interface allows it. Be extremely careful: using the wrong command, for example, instead of a lock, can lead to unpredictable results.

⚠️ Warning: Command Prompt does not forgive errors. Make sure you type the lock command, not firmware or manual partition formatting.

This method is especially useful when the Mi Unlock Tool GUI is not working properly or is giving out server connection errors. However, if the firmware on the device is not the original stock, the lock command may fail or result in a cyclical reboot.

Possible problems and ways to solve them

There may be various errors that require immediate response during the locking process, and one of the most common problems is the message "Unable to lock" or "Device is not Mi Official", which means that the device has a firmware that is not region-appropriate or a modified bootloader that has not been completely cleaned.

Another common problem is hanging on the Mi logo after locking, which often happens if there are artifacts from custom modifications, in which case you need to re-enter Fastboot mode and try to reflash the device through the Mi Flash Tool in "Clean All" mode, which is guaranteed to remove all traces of previous changes.

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If you lock your phone into an endless reboot, try using Recovery Mode (Power + Volume Up) and manually run Wipe Data/Factory Reset.

Also, users may encounter an “Anti-rollback check failed” error, which is a security mechanism that prevents the installation of an older version of the bootloader or firmware than the one installed earlier, which is impossible to circumvent by legal means, and attempts to do this can lead to irreversible failure.

Effects of blocking on the user

Once the bootloader is successfully locked, the device returns to full factory safety, meaning you can no longer install custom recavators or obtain root rights without re-unlocking, which is an advantage for some users because it eliminates accidental system breakdown.

It is important to note that re-unlocking a bootloader on Xiaomi requires a wait of 168 hours (7 days).If you lock the bootloader and decide to reopen it a day later, you will have to wait a week. This is a server-level restriction and you can’t get around it with standard methods.

It is also worth mentioning the loss of warranty in some regions if the service center detects signs of interference, even if the bootloader was blocked back, however, using official methods and stock firmware, it becomes almost impossible for the average user to detect the fact of previous unlocking software.

The final line is to check all the functions, make sure that the NFC, fingerprint and Face ID work, and sometimes after the lock, you need to reconfigure the biometrics, and if everything is working properly, you can consider the procedure a successful completion.

⚠️ Warning: Once the bootloader is locked, data recovery without a pre-built backup becomes impossible. Data encryption on modern Android doesn't allow you to simply copy files from memory.

Comparison of loader states

Understanding the difference between locked and unlocked states helps make an informed decision: a locked bootloader ensures maximum system integrity but limits customization; unlocked gives complete freedom but reduces security and can affect the operation of some applications.

For most ordinary users who are not engaged in modding, the state of "locked" is preferred, it ensures that even when you lose your phone, the data on it will be protected from the simplest methods of extraction. DRM-High quality content in streaming services.

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Locking a bootloader is a one-way process from a data perspective: you get security, but you lose the ability to flexibly configure without completely resetting.

The table below compares the key characteristics for both states.