I couldn't view a good picture of how the front panel circuit board is connected to the mainboard. I was thinking if it was a ribbon cable you could try to reseat it at either end (if they are plug in connectors), but from what little I could see (and that wasn't much), the front panel board might directly plug into the mainboard connector without a cable.
Can you identify any environmental condition that might be causing it to switch, like an air conditioner, refrigerator, etc. cycling on or off? It that's the case, sometimes a plug in supressor can be plugged inline with the offending appliance.
Is the amplifier itself plugged into some kind of power conditioner or filter?
Steve