If you have large files or want to ensure specific documents are safe:
FRP is an anti-theft feature from Google. If you reset the tablet via the Recovery mode (Method 2) without first removing your Google account in Settings, the system will lock you out immediately after the reset. How to Hard Reset NOKIA T21
This is common after a reset. Give it up to 10 minutes. If it stays stuck longer, force a restart by holding Power and Volume Up for 15 seconds. If you have large files or want to
Some Nokia models require being plugged into a charger or a computer via USB-C to trigger Recovery Mode. How to Hard Reset NOKIA T21
or is plugged into a charger to prevent it from shutting down mid-process.