I was driving my daughters 2013 E70 X5 and listening to music through Bluetooth from my phone. Apparently the volume was low on my phone, so I turned up the volume in the car to a normal level. When I changed to the radio, the volume went sky high momentarily, then went completely silent. There are no chimes or warning tones now either. The display still works fine, showing track names for CD's, radio station list, etc. There's just no sound coming out of any speaker. I checked all the fuses listed for the sound system and they are all fine. Is it possible that I blew the amp by overdriving it when I switched sources with the volume turned up too high? Any ideas?