From CPKB - Cell Phone Knowledge Base
Here are the secrets that Nokia corp. didn't told You.
 Also known as
- Nokia secret / secrets
- Nokia technique / techniques
- Nokia tips and tricks
 The tricks
 Symbian hard reset
- GREEN + 3 + * then power ON
- While holding the green and the "3" button and the "*" button press power ON for longer time. After a while "Formatting..." will appear on phone. It will erase all user data + applications + user code on phone. This method works 100% on 6600 mobile phone, but it may works on other older symbian nokia phones.
- RED + GREEN + CAMERA then power ON
- While holding the "RED" and "GREEN" and "CAMERA" button on phone, power on the phone. Phone will be hard reseted. It will erase all user data + applications + user code on phone. This method works on newer, touchscreen nokia symbian phones.
- LEFT SHIFT + SPACE + BACKSPACE then power ON
- While holding the "Left Shift" + "Space" + "Backspace" buttons, press and hold the power ON button till the phone asks for the country. It will erase all user data + applications + user code on phone. This method works on newer touchscreen nokias with full keyboard. Tested on Nokia N97.
 Operator logo on symbian phones
- Selecting operator logo
- Go to "c:/system/Apps/phone/oplogo" using Your file manager, then place a .bmp file in this folder then reset the phone! The file should be 97 x 25 pixels.
 Other tricks
- Start the phone in "safe mode"
- Press and hold the "pencil" key then power on the phone. Hold the pencil until the phone asks for PIN-code. In that case the phone will not start the memory-resident programs at startup.