Hum and left channel doesnt work

Question

Subwoofer is humming and the left speaker will not play. I checked continuity on the speaker out and found that the left channels positive and negative were shorted out. I disconnected the wires from the outfeed connectors in hopes that they were the culprit but found that it still hummed and shorted out when power was turned on. Does anyone know if one of the caps are known to go bad or if anything else is needed to be rewired. I never tampered with the wiring until there was a problem.