I don't know if you've checked the fuses for your audio system yet, but I'd recommend that. Sometimes, pulling the fuses for 30 secs, then replacing them solves some issues like this. Make sure the fuses are still in good shape when you take them out.
The fuse diagram is in the owner's manual or on the inside of the rear compartment opposite the CD changer.
I hope someone who's had this specific issue can chime in.
JV