Audio Issues

[dblmac]

(Skip to the end for a summary lol)
I’ve had my 135i since May of 2021, and before this one I had a 128i.
I never had a problem with my audio in my 128, but my 135 has been giving me issues since I got it.
There’s always been a constant static noise, coming from all the speakers when you listen close.. but especially from the rear right one, even when the car is turned off.
But now recently I’ve been redoing my interior, so my car is gutted. Only thing that’s in there is the driver seat and dash. No passenger seats, no center console, no driver foot well, no glove box, etc..
Audio was working fine, but all of a sudden my music won’t play, AUX or radio and there’s a loud cracking noise every couple seconds coming from that back right speaker.
When I was running diagnostics the radio came on, but stopped again. So now the radio will come on sometimes but my AUX still doesn’t work.
I guess to make a long question short..
Why does my radio only work sometimes, but my aux doesn’t and what’s up with the crackling sound.???
pls help driving without music is hell