To format a phone on power on (useful for phones which are unable to boot the system) turn phone off, press and hold the green (talk) key on the left + number 3 on the keypad + the * key and then turn the phone back on.
Apply on the following nokia phones:
3230, 6600, 6630, 6680, 3250, n70 and n73… other Nseries phones not yet supported..
Other way is just type: *#7370# and press ok.. enter your 5 digit security code which is 12345 by default
Formatting the phone on power-on is only supported by some headsets, including all Nokia Series 60 2.0 and newer smartphones (Nokia 6600 and up). Older phones like 7650 or 3650, or Series 60 smartphones from other manufacturers (e.g. Sendo X, SonyEricsson, Samsung etc….) do not support this function.
Warning: formatting the internal drive results in ALL DATA being removed. Use this only when you experience serious problems with your device. Do not touch anything during the process! It is recommended to only do it with fully charged battery and your phone connected to a charger to ensure that your battery doesn’t run out of juice in the middle of formatting.
Proven and Tested…