See my post above, #24
regarding how to do a hard reset.
It costs nothing, damages nothing, and sometimes fixes the radio.
You problem sounds a bit different is that I guess you do have sound/music but at a low level?
If so, maybe the hard reset will not work as for me, I get no sound a all, usually after a battery change out or new alternator being installed - something that totally depowers the 3 for awhile. I think it might be caused as a result of disconnecting the battery before the truck has gone to sleep and hence the audio software or whatever gets corrupted.
The hard reset seems to straighten that out, or whatever.
As I said, costs nothing and does not wreck anything and might solve the problem. If it does, let us know. I guess let us know regardless.
Water and the wires never seem to mix well.
Water collects in the under door sill channels and takes months to dry out but I do not think any audio system wires are there - mostly under the carpet thru the centre console and in the doors to the speakers.
That said, I also like the post #16
solution where the those wires are under the edge of the carpet and parallel the drivers door sill channel.