How to block the bootloader on Xiaomi Mi5: the complete guide

Owners of Xiaomi Mi5 smartphones, who decided to return the device to a factory state after experimenting with custom firmware, often face the need to close access to the system partition. Locking the bootloader is the final stage of a complete restoration of the gadget, ensuring the integrity of the software and the security of user data, this process returns the phone to a state identical to the one in which it was sold.

However, it is important to understand that the procedure is not always irrevocable. In some cases, the system may require re-authorization or verification of rights, but for most users, closing the bootloader means the final transition to a stable official version of MIUI. It is important to be aware of the risks and prepare the device for manipulation to avoid software errors.

In this article, we will discuss in detail the technical aspects of closing the bootloader on the flagship of 2016. We will look at methods through official utilities and specific commands relevant to the architecture of the Snapdragon 820, on which the Xiaomi Mi5 is based.

Why do I need to lock the bootloader on the Mi5?

The main function of the bootloader is to check the integrity of the operating system before it starts, and when the Bootloader is unlocked, this check is disabled, which allows you to install modified versions of Android, while blocking returns the digital signature mechanism, preventing the launch of any software that does not have a manufacturer's certificate.

For the average user, this ensures that even if a device is accidentally infected by malware that has infiltrated system files, the phone will refuse to start the damaged system, creating an important security barrier, especially if the device stores banking applications or sensitive data.

⚠️ Warning: Before starting the procedure, make sure that the phone has the stock (official) firmware installed. If you try to block the bootloader if you have a custom recovery or modified core, the device will go into an endless restart cycle (bootloop).

In addition, a closed bootloader is required for some features, such as Google Pay (now Google Wallet) and banking applications that use Android Pay. Many financial institutions block their services on devices with open access to system partitions.

Also worth noting is the performance impact. While the difference is minimal, a locked-down bootloader stock system is more predictable, as it doesn’t waste resources checking modified startup scripts, especially for the Xiaomi Mi5, whose age already requires optimizing every megabyte of RAM.

Preparation of the device for the procedure

Before you start active, you need to perform a number of preparatory operations. Ignoring these steps can lead to loss of data or inability to boot the system. First of all, make a full backup of all important files, as the process is often accompanied by a complete reset.

Make sure the battery is at least 60% powered, the process of flashing and changing the status of the bootloader is energy intensive, and a sudden power outage at a critical moment can lead to irreversible damage to the software part of the memory chip.

You will need a computer with Windows operating system, as most official utilities from Xiaomi are sharpened for this platform. USB-Android drivers so that your computer can correctly recognize your phone in Fastboot mode.

Don’t forget to turn off the Find Device feature in your Mi Account if it’s activated, otherwise, after locking the bootloader and resetting, the phone may request a password from the previous account, which will create additional difficulties when you first set up.

Check the current status of Bootloader

Before you try to lock something, you need to know exactly the current state of the system. On the Xiaomi Mi5, the bootloader status is displayed when you turn on. Press both the power and volume buttons to go to Fastboot mode.

The screen will show a picture of a hare repairing an android and say orange or unlocked if the bootloader is unlocked. If the device shows locked status, then no additional action is required - your phone is already protected. However, if you reflashed the phone manually, the status may be lost.

You can get more accurate information through your computer, connect your Fastboot phone to your PC, open the command line, and type in a status check command:

fastboot getvar unlocked

If you get yes, the bootloader is open. Answer no indicates that the lock is already active. This command works at the Fastboot protocol level and gives the most reliable result, ignoring possible visual interface bugs.

It is important to distinguish between software unlocking through the developer settings and the physical state of flash memory. Even if the phone menu says that the device is unlocked, the actual flag change only occurs after confirmation by Xiaomi servers.

The method of blocking with Mi Unlock Tool

The safest and most official way to get things back to normal is to use the Mi Unlock Tool, which is more commonly associated with unlocking, but also allows for reverse action if your phone is connected to the Internet and your account is logged in.

Run the program on your computer and log in to your Mi Account. Connect your phone in Fastboot mode. If the device is in a drain state, the utility may suggest updating the firmware or synchronizing status. In some versions of the software, the Unlock button changes to Lock if the detects system is open.

• 🔌 Connect the cable. USB 3.0 directly to PC motherboard, avoiding hubs.
• 🔑 Enter the username and password from Mi Account, which was used to unlock previously.
• 🔄 Press the lock button if it is active in the program interface.
• ⏳ Wait until the process is completed, which can take up to 10 minutes.

It should be noted that this method only works if the phone is the original firmware. If you installed custom software (for example, LineageOS or Pixel Experience), the utility Mi Unlock will refuse to lock, giving a compatibility error.

⚠️ Warning: Do not interrupt the locking process even if the phone screen is out or the program appears to be getting stuck.Forced disconnection of the cable at this point can lead to the "bricking" of the device (Hard Brick).

If successful, the phone will automatically restart and begin the process of cleaning data, a routine behavior of Xiaomi’s security system, ensuring that after the bootloader is closed, there will be no trace of third-party interference in the system.

Blocking through Fastboot commands

For advanced users who are confident in the integrity of their firmware, there is a method of manual locking through console commands, which requires extreme caution and understanding the structure of Android partitions.

To perform the operation, the phone must be put into Fastboot mode. Connect the device to the computer and open the terminal in the tool folder. ADB/Fastboot. The main command for blocking is as follows:

fastboot oem lock

Or, depending on the Xiaomi Mi5 bootloader version, you may need to command:

fastboot flashing lock

Once you have entered the command, a warning will appear on the phone screen that all data will be deleted, which is usually confirmed by volume buttons, and the system will again warn of the risks, as this action is irreversible without re-unblocking.

If the command is successful, the terminal log will have an OKAY message, and then you need to reboot the device, and the important thing is that if the phone doesn't turn on after that command, then there are modified files in the system partition that the bootloader refused to sign.

Status and state table

To better understand the processes that are happening with your Xiaomi Mi5, consider the basic conditions of the bootloader and their characteristics.

As you can see from the table, Locked status is the only one that is right for everyday use of a device by the average user, and it provides a balance between functionality and data security.

Testing status is typically found on devices designed for developers or on phones stitched with engineering firmware. It is rare on civilian versions of the Xiaomi Mi5.

Possible problems and solutions

When you lock the bootloader on older flagships like the Mi5, you can have specific errors, and one of the most common is a failure to execute a command due to a mismatch in the firmware version, which is treated by flashing through Mi Flash in Clean All mode.

Another problem is network loss, or IMEI. This happens if you lock it, and you damage the persist partition where the modem calibration data is stored. For the Xiaomi Mi5, this is critical, because it's almost impossible to restore this partition without a backup.

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Save the persist section before any manipulations with the bootloader. Backup command: fastboot flash persist.img (requires a pre-made dump).

If the phone went into a bootloop (cyclic reboot) after locking, the only way out is to re-unlock the bootloader, flash the stock image firmware and then try again to lock.

You can also have a phone that's locked, but the status in Fastboot is not changed. It's a software glitch, so you can focus on the phone, and if it boots without unlocking warnings and it passes integrity checks, it's a success.

Frequently Asked Questions (FAQ)

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Bootloader lock is the point of no return for custom modifications. Make sure you don't need Root rights and custom recavers anymore.

To sum up, locking the bootloader on the Xiaomi Mi5 is an important step for those looking to return stability and security to their gadget.

Use only proven firmware sources and official tools. Remember that the Mi5 is a legendary, but already age-old device, and its software requires careful treatment when manipulating low-level system partitions.