If this is OT, does anyone know where I should post?

My car radio/cassette player has taken to switching itself on and off at
random, even when stationary with the ignition turned off (this latter
drains the battery). Since it doesn't lose the security code when it
switches off, I feel that it cannot be losing connection to the battery. I
have, of course, removed it from the car.

Has anybody seen this sort of behaviour, or have any good ideas. I'd be
grateful.

GPG