Help fixing a Kenwood KRF-V5300D Home Theatre Receiver PLEASE

Recently I've had some problems with my amplifier. It started that every time i would turn it on from the power switch it would turn off after about 2 seconds (it was on component Video 2) On any other component like AUX or Video 1 it did work fine. I re-plugged the optic fiber cable (i think thats what its called - the one that transmits through light) and it began to work. This lasted for a few days. Finally, none of the components work and it turns off after two seconds no matter what it is set on. Could this be a problem with it over-heating? Or playing sound too loud. Any suggestions as i can't replace it readily.
Any suggestions would be great.
Thanks, Liberty.

Sounds like the processor within the amp is detecting a fault and shutting itself down.
A wild guess but possibly dc on the output or a power supply fault would be the first things I'd be looking for.