Where to Troubleshoot

[stal023]

I have an 06 that was installed with the GROM BT3 unit. Everything sounded amazing until a couple weeks ago. At first I thought my front speakers were trash but upon listening closer, ALL my speakers sound like the bass has been blown. I also hear a new rattle noise (sounds like it is inside deep near the CD player) when I start up the car, but only upon start up. Seems suspicious. I believe I have the premium sound but I don't know that for a fact because well, this is all new to me. I know it has an amp and the GROM unit in the back and a CD player up front. Any advice on where to begin to troubleshoot? Seems like it could be a connection issue. THer horrible sound is driving me CRAZY.

[stal023]

Okay, I got back to the amp area and there are 4 things unplugged. I have NO idea what they are and if they should be plugged in and if they are, what connects to what. Can someone take a look at the photos and let me know?





https://photos.app.goo.gl/pJKJj8zjvpKtb8Kc7
https://photos.app.goo.gl/qNn1pb6ReoQZJQDe9
https://photos.app.goo.gl/6u5bSmswVP57XqkDA