41CL locked up

[JurgenRo]

My 41-CL (V4 board) does not switch on with the On-button. By chance I figured that the only way to switch on (and switch off) the unit is with the Backspace button! But it merely comes up with a Display containing only @ signs. Absolutely no response to keystrokes.

I tried to get a Memory Lost condition by removing batteries (left them out for about 12 hours), short-cutting the battery poles and also with the reset keystroke combination (Backspace - On). But nothing helped. Also, the machine does not switch off automatically after some time of inactivity.

Would appreciate any ideas to get it back to life ...