A couple of months ago, I have listed some secret codes on S60 phones to display various useful information. Some of the readers have provided some feedback to me with more secret codes. Here they are:
*#92702689# (*#war0anty#) – Display the life timer information of your S60 phone, i.e. the total time of phone call (in minutes). Some users have asked how to reset this timer; as far as I know the only way to reset it is by flashing the phone.
*#7780# (*#rst0*) – This will soft reset your phone. It is different from *#7370# because all data, like contacts, calendar and notes, are not removed. It will only reset the phone settings, such as profiles, themes and shortcuts. The default lock code is 12345.
There is another key combination which is used to hard reset the phone (similar to #*7370). It is useful in some cases, for example when the phone cannot reboot. The trick is by switching off the phone then press and hold Call key (Green key) + * key + 3 key + power button for a couple of seconds.
Note that you have to press and hold the four keys at the same time; otherwise it won’t reset the phone. This key combination doesn’t work on some S60 phones.
Update (12-Aug-06): Thanks to Jukka for the correction. You don’t need keep pressing Call key + * + 3 + Power.