Powered Subwoofer (JBL Venue Sub12) Makes Pop Static Noises When Loud

I have a JBL Venue Sub 12 powered subwoofer that I bought (knowing the amp had some issues). I just want to learn a little about troubleshooting a broken circuit and was wondering if anyone had any tips about what could be wrong with the amp. There is a video of the problem at https://youtu.be/yvfCJoarNj0 if you want to take a look!

Basically when the volume is turned up slightly loud it starts making these popping static noises. There is also a small crack in the circuit board (off R9), not sure if this may be causing the problem. It is shown in the picture below.

Anyway, I would appreciate any insights.

Here is the schematic diagram. Layout 1

Thank you.