1.Speakers hooked up incorrectly or to speakers not recommended by manufacturer requiring more power-especially if using alot of BASS ( wires if touching might have shorted unit ).
2.Internal cooling fan non operational ( probably due to dust ).
3.Amplifier-or chips related to it- burnt out (usually due to playing music too loud for an extended period of time ).
Fixing:
1.Hook the factory speakers up correctly ( hopefully it's not too late for this ).
2.Take cover off blow dust off fan ( or take unit to a trusted person to do so-might need replaced ).
3.If you are like me and love the BASS you probably fried the amplifier while jamming the music with 15" subs-especially if the subs started to sound odd on the hard bass notes for maybe 10 seconds before it completely stopped working. Solution; buy another unit that IS designed to work with BASS and then you won't be in this situation again.A grown man crying due to his music blowing up,is not a good site to see-it can also be embarrassing jamming some Public Enemy and having it make all kinds of weird noises right before meltdown-LOL.......good luck......
karl
September 2011