2015 Audi Q5 B&O audio system, quit working
 

I have an 2015 Audi Q5 TDI premium plus with the B&O audio system and it just quit working, display still works, Nav maps come up, phone interface still works but no sound, any Idea's?

Blown Amp
 

Or you could hunt down a fuse related to the amp. B&O amps fail often and early because of their stupidly cheap engineering specifications used for ICE class d amplification.

If the amp was unpowered due to blown fuse, the MMI 3G system would go down entirely due to the broken MOST ring.
Scan for DTCs would be a starting point; since the ring is up, the J525 should be able to respond to a query.
But also look for other things, like is the mute on. Try the full MMI reset (I don't know the MMI 3G+ B8.5 era reset offhand).

But if the guy hasn't come back since July to follow up on his post, ....

True: Could Be User Error
 

Radio Off = Radio Mute on these systems.

But this being a B&O system it most likely has an ICE power amplifier module with a built in fuse on the board near the power supply, which is not user replaceable. That could be the source of the problem, although you would need to open the amplifier itself to see the damage.

should have said this earlier, talked to the service dept. at the dealer, he told me to turn on the car without the engine running and hold down the volume/power button until the display hadi the Audi screen on it, about 10 seconds, make the head unit reboot and it worked after that