GSM-Forum - Hard Reset NOKIA LUMIA with Hardware Button Key

Now we have other option to hard reset or format NOKIA LUMIA 620 with hardware key button especially when the phone stuck or can not access to menu :

A. BIG STEP ONE:

Please remember, we have to do two BIG STEP, do it step by step
Turn off the NOKIA LUMIA 620
BIG STEP ONE (a). Press and Hold the Power Button, do not release until the phone vibrate (if you feel the vibrate in NOKIA LUMIA 620 then release the Power Button)
BIG STEP ONE (b). Press and Hold the Volume Down Button, do not release until the LCD show the exclamation mark (if you see the exclamation mark in LCD, then release the Volume Down Button)

B. BIG STEP TWO (for this step, we need to finish all BIG STEP ONE first)

To continue reset, you have to do the last step bellow:D
Press Volume Up Button Key and release
Press Volume Down Button Key and release
Press Power Button Key and release
Press Volume Down Button Key and release
The the NOKIA LUMIA 620 will do the hard reset format, wait about three until five minutes. While waiting you will see the gear appear until it finish.