Hello everyone, I'm brand new to these boards. I bought a 2012 C350 Sport with 30,000 miles last week.

I've been super happy with the vehicle except something came up on my way to work this morning. I couldn't find anything anywhere on the internet regarding this issue, so I figured I would see if y'all knew what the issue could be. The rear speakers (I think it's the rear deck sub woofer/tweeter), started to crackle... about 10 minutes later an extremely high pitched screeching started to emanate from the rear of the car (It's unbearably loud). Attached is a video I recorded on my phone. It sounds like a grounding issue to me. Has anyone experienced anything like this? I'm not averse to popping a few panels to get at the wiring, just wondering if anyone had anything like this and looking to tap into some experience that someone else might have.

Many thanks!