SL930H: Boot menu/ Reset

The handset needs to be switched off.
Press and hold down the Home and the left key.
Switch on the device (right key) and hold the other two buttons for 3 seconds.
Then you must release right key and afterwards the two other keys.

After startup you can see different options:
Reboot system now -> Restart, leave menu
Apply update from external storage -> To update the system via micro SD card
Wipe date/factory rst w/o dect -> Factory Reset without DECT registration data
Wipe cache partition -> Not needed
Wipe date/factory rst w dect -> Factory Reset with DECT registration data
Apply update from cache -> Not needed