See also:

Deleting all stored programs
Press the left and right memory buttons for approx. 20 seconds until the LED flashes rapidly. All stored programs are deleted. The programs cannot be deleted individually. ...

Maintenance
The battery is maintenance-free, i.e., the electrolyte will last for the life of the battery. Your service center will be glad to advise you on questions regarding the battery. ...

Screw thread
Push out the cover by pressing on the top edge. ...