Symptoms - VERY QUIET audio, was barely audible with my audio amp all the way up
Solution - There was a single burnt resistor, R13, which was just a 1k ohm resistor. After replacing that and the damaged capacitor that was next to it. The resistor is connected to the 5V rail, so based on the fact that it burned up makes me question whether or not the power rails were swapped around on accident. I got half a hacked harness in the box, so that further supports this theory.
Anyway, this one is good to go, remember to hook your harness up right!