Something similar appened on my Beo 7, there were some problems, first a fuse burned (all working but no possibility to actuate commands) AND the main relay with a defective contact (after some minutes turntable stops and the beo goes in GURU mode [no operations possible]) AND a capacitor broken...
If you can open the unit (only the control section) check the fuses and the main relay, Martin has the best capacitors kit, I suggest you to try to change them, It is not so difficult and in the kit there are detailed instructions.
After this I am here to help you
ciao ciao
Eugenio