No audio at all. Every other quadrant works fine (Phone, BT, Maps, climate control). But no audio at all. Even when I press buttons on the screen that work. When I try to turn on the system with the hard button, entertainment quadrant reports (at the bottom of the quadrant) "Entertain. Not avail." and refuses to turn on. I've done a master reset of the unit. Could it be a fuse ? Any other ideas ? I recently updated the firmware, but that was weeks ago. Thx.