How To Unlock Bootloader Using the File ? Download Xiaomi MI8 BL Unlock File. Install USB driver on your computer. Open flash tool and locate the BL unlock file. Now, connect your device into flash/edl mode. Now, click on the start button. After flashing the BL unlock file, then connect your device into fastboot mode. Open the bootloader unlock tool. Now, click on unlock button. link file unlock bootloader