Bootloader Unlocking (first step)
Alessandro G. - Translated by matt_zer01I am not responsible for bricked phones, microSD deaths, thermonuclear wars or fires caused by the failure of the security alarm. Inquire before taking any action explained in the guide.
ATTENTION: unlike other brands, for some time now Xiaomi has decided to put a time block. This means that, once the procedure illustrated here has been carried out, you will necessarily have to wait for a certain period of time. Normally this would amount to 3 days, but recently the company has extended this block and in some cases you may have to wait even 1 month (720 hours). In the case of the Mi9 SE, the waiting hours amount to 360.
Before continuing, what does unlocking the bootloader involve? This block is set by Xiaomi to prevent third-party resellers from installing rude and potentially harmful ROMs for users. ATTENTION: unlocking it will result in the loss of data on the phone. Therefore it is highly recommended to make a backup of the files you are interested in keeping.
And what about the warranty? For products sold directly by Xiaomi Italia the same company has confirmed that unlocking the bootloader does not invalidate the warranty. In the event that the device has been purchased from other parties, we invite you to ask directly to the seller in question.
- Chapter 1 - Create My Account
The first step to take to perform the bootloader unlocking procedure is the creation of your Mi Account. In case you have already done so, you can jump directly to the second chapter. So, first of all, go to the official page of Xiaomi and create your Mi account.
- Chapter 2 - Entering My Account
Once you have created your Mi Account, you will have to associate it with the smartphone you want to unlock the bootloader. Here are the steps to follow:
1) Open the "Settings" or "your language settings", depending on the MIUI language;
2) At the top click on "About phone" or "My Device";
3) Click repeatedly on "MIUI Version" or "MIUI Version" to enable the "Developer Options" or "Developer Options";
4) Go back to "Settings", scroll down and click on "Additional Settings";
5) From here select "Developer options" and enable the toggles for these three items: "Developer options", "OEM unlocking" and "USB debugging";
6) Click on "Mi Unlock Status" or "Mi Unlock Status";
7) At the bottom click on "Add account and device";
8) Enter the data of your Mi Account and click on "Sign In".
- Chapter 3 - Unlock the Xiaomi bootloader (after the required waiting time has expired)
Once the previous steps are completed, here comes the crucial point of the bootloader unlocking procedure. To complete everything we will have to use Mi Unlock, the official software provided by Xiaomi itself.
1) Download MiUnlock from the link above, and unzip the zip file into a folder at will;
2) Inside the unzipped folder, start the file "miflash_unlock.exe";
3) In the disclaimer screen that appears, click on "Agree";
4) Enter the login data of your Mi Account that you have associated with the smartphone;
5) Turn off your smartphone;
6) Hold down the Power button and the Volume- button to start it in Fastboot mode;
7) Connect it to the PC via USB cable;
8) If everything went as planned, "Phone connected" will appear in Mi Unlock;
9) Click on "Unlock";
10) Click on "Unlock anyway" in the disclaimer that will appear ";
11) Once the unlocking is complete, the green "Unlocked successfully" message will appear;
12) Click on “Reboot phone” to restart it correctly.
- Chapter 3 - Unlock the Xiaomi bootloader (after the required waiting time has expired) (For Linux / Mac users)
If you are on a Linux/Mac machine, you should use the XiaoMiTool V2 for unlocking your device's bootloader without using a Windows machine. More info here (the original XDA page by the maker of the program) and here for downloading the program itself. I'll add the steps in the future if requested, but they're already well-explained on the XDA post.