Dumb question but the power balancer leads (wires that power the speaker system) are going to the correct terminals on the battery now too right?
Well, either the positive wire to the system is shorted to ground or the system is shorted. So check the wiring carefully first. Then you will know for sure. My guess is you cooked the radio.… I guess I should also add that the audio system was operating just fine before I messed up the battery polarity. I’d have thought the fuse would have protected from damage but….?