Blaupunkt Travelpilot blank display

[PeteG]

Right. Got a 51 plate Octavia with a Blaupunkt Travelpilot, with removable faceplate. It was working perfectly, but now when it's turned on it plays the one radio station, and won't do anything else. None of the illumination works, none of the buttons do anything.

Any ideas where I need to start fault finding? I've given the contacts between the plate and the stereo a clean, with no effect.