No audio sounds (no music, door chimes, turning signal sound)
 

Since a couple of weeks now, my audio is completely gone, even tho the head unit comes on. I can use navigation, but I can’t hear it, because of course... no sound. I had the car in the dealership, they plugged it up to their computers, they couldn’t find anything. I sent the amp in to united radio, they tested it and it is completely functional. Has anyone experienced this before and what was the fix? Btw, I own a CTS 2013, with the pop up head unit, I have the factory boss amp and speakers in it as well.