Owning a Xiaomi Mi6 gives users a lot of customization, but sometimes it is necessary to return the smartphone to its original state. The request for how to lock the bootloader on this model often arises from those who have previously experimented with firmware or want to improve the level of security of the system. The bootloader is the first piece of the software shell that starts when turned on, and its status directly affects the ability to install third-party software.
The bootloader closure procedure is not a standard feature available through the standard Android settings menu. Unlike unlocking, which is done through official tools, the reverse process requires a deeper understanding of the structure of memory partitions. Full bootloader lock is only possible if the stock backup and the original firmware are available. Any deviations from this state can lead to the device’s failure.
Before you start to act, you need to be clear about the difference between flashing and locking directly, and users often confuse these concepts to simply clean the phone of the modifications. It is important to understand that the Mi6 is a device with a specific life cycle, and manipulating its system partitions requires carefulness.
Why you need to lock the bootloader on Xiaomi Mi6
The main reason owners want to shut down the bootloader is to protect personal data. Open loader theoretically allows access to the device memory even without a password, if the attacker has physical access and the appropriate skills.
In addition, some banking applications and services with high security requirements may not work properly on devices with an unlocked bootloader. Although root rights are usually the main trigger for blocking such applications, bootloader status also plays a role in the system integrity verification algorithms (SafetyNet/Play Integrity).
Another aspect is preparing the device for sale: Consumers are often wary of open-loader smartphones, as it indicates interference with the code. The return of the Xiaomi Mi6 to a “shop-like” state increases the liquidity of the gadget in the secondary market.
- 🔒 Increasing the level of protection of personal data from unauthorized access.
- 💳 The correct operation of banking applications and NFC-payment.
- 📈 Increase in the cost of the device during resale.
- 🛡️ Checking system integrity at start-up.
⚠️ Attention: Blocking the bootloader on custom firmware or in the presence of root rights is guaranteed to lead to a "brick" of the device.
Critical requirements before the procedure
The most important condition for successful locking is the presence of original, stock firmware. If your Xiaomi Mi6 has a custom build installed (for example, LineageOS, Pixel Experience or MIUI EU with modifications), the procedure for closing the bootloader is impossible without a rollback. The system will check the digital signatures of the partitions at start, and if there is a discrepancy, it will refuse to boot.
The second requirement is that you don't have any modifications to the system partition, and even if you're using the official firmware but you've previously obtained root rights or made changes to system files, locking the bootloader will block the system from starting, and all changes must be completely removed, and the system, boot, and recovery partitions must meet the benchmark.
It is also critical to check the status of the Mi Account. The binding was required to unlock, but for the reverse procedure it is important that the phone is not in the search mode (Anti-theft), although after flashing on the stock this is usually solved by logging into the account. Make sure that the battery is charged at least 60%, since the process of rechecking partitions and restarting is energy intensive.
☑️ Checking the device's readiness
Instructions for returning stock firmware
Since there is no direct command to lock the menu, the first step is always to completely reflash the original way. For Xiaomi Mi6 (codename sagit), you need to download the Fastboot firmware archive with the.tgz extension, not Recovery (.zip). Using Recovery firmware through Fastboot mode will not allow you to re-mark the partitions correctly.
The process is performed using the Mi Flash Tool utility on your computer. After unpacking the archive with the firmware and installing the drivers, you need to transfer the smartphone to Fastboot mode by pressing the volume reduction button when connected. USB-In the program, select Clean All mode, which completely erases data and reassembles partition structure.
flash_all.batScript launch flash_all.bat It starts the process of recording all images, and you can't turn off the cable or interrupt the power, and when you do that, the phone automatically restarts to the clean system. MIUI. Only in this state can the question of blocking be considered.
| Type of firmware | Expansion | Method of installation | The result |
|---|---|---|---|
| Fastboot | .tgz | Mi Flash Tool | Complete cleaning and re-marking |
| Recovery | .zip | Through the Recovery menu | Update without data loss |
| Recovery | .zip | Mi Flash Tool | Not supported |
| Fastboot | .tgz | Through Recovery. | Not supported |
What to do if the Mi Flash Tool is in error?
The lock mechanism via Fastboot
Technically, the bootloader lock on Xiaomi Mi6 is done through the Fastboot command.However, unlike many other manufacturers, Xiaomi has implemented an authorization server check. The fastboot oem lock team on Xiaomi devices often doesn't work or requires a special token that is issued only when officially unlocked.
There is a nuance: on many global versions of MIUI firmware, the lock command is simply ignored or returns an error if the device was not specifically prepared by the service center.
If you are using a global firmware version, most likely the standard command is:
fastboot oem lock...will not perform the expected action or require confirmation that cannot be given without an unlocked screen (which may not boot).In some cases, the fastboot flashing lock command helps, but it is relevant to newer Android standards, whereas the Mi6 uses older protocols.
- 📱 Connect your phone in Fastboot mode to your PC.
- 💻 Open the command line in the folder with ADB/Fastboot.
- 🔍 Enter the status check command: fastboot getvar all.
- 🔒 Try the lock command (with caution).
⚠️ Note: Do not use the "lock" command if the device status bar shows "unlocked", but you are not sure of the origin of the current firmware at 100%.
💡
On Xiaomi devices, bootloader locking is often impossible without special tools if the device has been officially unlocked before.
Alternative methods and their risks
There are some online references to bootloader locators, programs that supposedly close the bootloader without losing data. For the Xiaomi Mi6, these tools are extremely risky. They work by writing directly to memory, bypassing signature checks. A byte error can permanently disable the processor (hard brick).
The only safe alternative is to go to an authorized service center, where engineers have access to closed Mi tools that can force the loader to change status and reflash device-specific data, but for a discontinued Mi6, this service may not be available or cost-effective.
Users also sometimes try to flash recovers from another model or region, which causes the phone to stop seeing. SIM-card, fingerprint scanner is not working or camera gives out black screen. Mi6 are tightly tied to specific kernel versions.
It's worth mentioning that some users confuse locking the bootloader with setting a password to log in to Fastboot. These are different things. The password protects against flashing, but doesn't change the status of the bootloader itself in terms of verifying Android signatures.
Possible problems and ways to solve them
The most common problem after a lock attempt is that the device gets into a bootloop cycle. The screen lights up, the Mi logo appears, and the phone goes out again. This means that the partition signatures do not match the expectation of a closed bootloader. The solution is to reflash stock through Fastboot.
If the phone is no longer computer-defined and no longer responsive to buttons, it may have gone into Emergency Download (EDL) mode. For the Xiaomi Mi6, exiting this mode often requires disassembling the case and closing the test points on the board, since the match button may not work.
Another problem is the loss of IMEI. If you block or flash it incorrectly, you can erase the persist and modem partitions. Restoring IMEI to Xiaomi is a complex procedure that requires backup of these partitions made before the experiments. Without a backup, it is almost impossible to restore unique identifiers legally.
💡
Always make the backup of the persist partition with the command "fastboot flash persist persist.img" (if there is a backup) before any manipulations, as it stores sensor calibrations and IMEI.