At its last but one refusal to work atall I cleaned all the aerial contacts in the boot electrics this was successfull with one aerial errection.
At the last refusal today it was obvious that the problem lay with the head unit as when the on button was pushed there was a brief display flash but no turn on.
I removed the on and balance control button thingos and hit it with contact spray--no result--no suprise.
Put a tape in and horay worked --and then not to be outdone so did the aerial --

Anybody know what the problem may be , the damned aerial is working fine now but --------------------