One of the benefits of unlocking the bootloader is you can install Custom ROM or TWRP recovery via Fastboot Mode. There are two ways to unlock the bootloader, officially and unofficially. Officially, you must make an unlock request to Xiaomi Developer Team. Unofficially, we need a custom file like emmc_appsboot.mbn but be careful, changing the emmc_appsboot.mbn file can cause your device to be brick.
On this topic, I will share the experience how to unlocking the bootloader in an official way.
Request Unlock Bootloader
- You must be on China Developer ROM to unlock your device. If you're on MIUI China Stable then please download MIUI China Developer ROM. If you're on MIUI Global Stable then please proceed and download MIUI Global Developer ROM.
- I assume you already have MI Account. Log into the Mi account which has acquired unlocking permission on your device.
- Go to http://en.miui.com/unlock/ and click Unlock Now.
- Login using your MI Account.
- On page http://www.miui.com/unlock/apply.php. Please input your name, mobile number, and please provide the real reasons why you want to unlock your phone in English. Copied reasons from other tutorials might cause your unlock application to be rejected.
- Apply Now.
- If you haven't get sms from Xiaomi after 2 weeks, please post a thread here http://en.miui.com/type-64-717.html. Provide information such as :
- Mi Account UID:
- MIUI version:
- Your device:
- Screenshot of the unlocking page status
- Days of application:
What you should do after received the approval SMS for unlocking bootloader?
- Turn off your device, press the Power button and Volume Down button at the same time to enter fastboot (bootloader) mode.
- Download and install Unlocking Tool on your Windows PC.
- Log into the unlocking tool on PC with the same Mi account. Connect the device with the PC using USB cable.
- Press Unlock. The unlocking process will complete in about 10 seconds.
- Unlocked successfully. Reboot phone.
After unlocking bootloader, users will be able to flash fastboot ROMs and custom ROMs. The unlocked device will be marked in the official service end. Users could lock bootloader again by flashing official MIUI ROMs. (This will need to use fastboot oem lock. Please note to flash offcial MIUI ROMs, otherwise your system won't be able to start)
- After getting unlocking permission for a Mi account, users can unlock the verified device immediately. One Mi account could only unlock one device within 30 days.
- Users could require for unlocking permission in this site: http://en.miui.com/unlock/.
- If a prompt says that the current account is not logged into a connected device. Please log in with this account on the device that needs to be unlocked.
- If your device is encrypted, unlocking bootloader will wipe all user data. Please perform a backup beforehand. If your application has been rejected, please try to apply again later. And please input the real reason that you want to unlock your device in English. Don't copy and paste others' unlocking reasons.