WITH PHONE SWITCHED OFF
1. Press and hold soft1 and soft2 keys (i.e. menu keys).
2. Press and hold power button for around 1 to 1.5 seconds. Release power button. Keep holding both soft keys.
3. After a while, black screen should show instructions asking user to press '0' key to reset to factory default.
4. Press '0' within the timeout period (which is very brief).
5. If instructions don't appear on the screen, repeat steps 1 to 4.