Follow these steps precisely. Timing is critical.
Continue holding both buttons down. After a few seconds, the screen will light up and you will see the NOKIA logo appear. How to Open Recovery Mode on NOKIA C21
If you see an Android robot icon with the text "No Command," you must use a specific sequence to enter the actual menu: Press and hold the . While holding Power, quickly tap the Volume Up button once. Follow these steps precisely
Check that your Volume and Power buttons click freely. Clean around the edges with a dry toothbrush. If still faulty, contact Nokia service center. How to Open Recovery Mode on NOKIA C21
If your Nokia C21 can still boot to the home screen but you want a shortcut to Recovery Mode, you can use a PC or a terminal app.