You are now in Recovery Mode on your NOKIA T21.
Press this to confirm your highlighted selection. Common Options You Will Find: How to Open Recovery Mode on NOKIA T21
: Once the Nokia logo or the T-Mobile branding appears on the screen, release the Power button but continue holding the Volume Up button . You are now in Recovery Mode on your NOKIA T21
Don't panic if you see a dead Android robot with the words "No Command" written underneath it. This is a normal security screen! To get past it and enter the official recovery menu: Press and hold down the . How to Open Recovery Mode on NOKIA T21
Below is a complete, ready-to-publish blog post walking you through the entire process.