First thing check all ground and power wires and make sure ur rca wire make sure it isnt cut in anyway. after that unplug ur sub and unplug the negative wire from ur amp, while its out check the fuses on the amp if all is well put all fuses back if not get new. then plug the negative wire back in if protect goes off check for heat and if no heat inspect the wires from speaker out put all the way to the sub, look for any wire touching another this is were most problems are even the smallest wire can trip a protect. if u still cant find the problem. an amplifier specialist is in order.if its trashed go on ebay and buy a powerbass there goin cheap right now. hope i could help