Here’s the fix:
Recovery Mode is a vital diagnostic tool on Android devices, including the Nokia T21 tablet
: When the Nokia logo appears, release the Power button but continue holding Volume Up0;b2e; until the "No command" screen (a dead Android robot) shows up.
Wait 10 to 15 seconds for the device to vibrate and shut down completely. Step 2: Trigger the Fastboot/Bootloader Screen