Connect your Nokia T20 Wi-Fi to your computer using the USB cable.
On some Nokia devices, the initial screen is Recovery Mode. If you see a "No Command" screen with an Android robot: How to Open Fastboot Mode on NOKIA T20 Wi-Fi
Once in Recovery (the screen with the "No Command" robot), hold and tap Volume Up once to see the menu. Connect your Nokia T20 Wi-Fi to your computer
If your tablet can still boot into Android, this is faster. How to Open Fastboot Mode on NOKIA T20 Wi-Fi
(do not release yet).
Opening on your Nokia T20 Wi-Fi is a standard procedure for advanced troubleshooting, flashing firmware, or performing a manual factory reset when the standard menu is inaccessible. Method 1: Manual Button Combination