No sound or Bluetooth

When I power on my JBL Partybox 300, it starts up but there’s no sound. I can turn on the lights and the bass boost, and everything else seems to work normally. Unfortunately, I can’t turn on the Bluetooth.

I’ve tried hard resetting the Partybox and even updating the firmware, but that didn’t fix the issue.

I also replaced both ribbon cables for the button control PCBs, since they were damaged, but that didn’t solve the problem either. It seems like there might be an issue with the mainboard. I’m wondering if anyone has encountered the same problem and maybe knows where to look, because I took out the mainboard and didn’t see any obvious damage.

I don’t think there’s an issue with the power supply, since it charges the battery and the box powers on even without the battery connected.

If anyone thinks they can help or has a possible solution, I’d really appreciate it!