Dropped a BT connected call, since, have no speaker volume w radio, cd, phn. on 2005 BMW X5

Fuses & wire connections intact, radio lights, cd/aux/BT functions all appear working, but zero sound. Note, car battery was replaced by dealer the day before. What is rec next step for repair/troubleshoot? It's become a very quiet, tiring drive!

Asked by for the 2005 BMW X5
Did you ever resolve this? I have the exact problem- started yesterday- and I am beyond frustrated!