Audio and lcd display not working
 

I was sitting in a drive thru. All of my warning lights came on at 1 time and my power steering and audio system and lcd display went out. I discovered after troubleshooting that my alternator went out. I replaced it and all the warning lights went off and power steering started working.
My audio head unit and my lcd display still doesn't work AC and heat work fine.
so far I have
pulled the unit and checked the pins in the front
checked the cabin fuse all related fuses and all relays.
Disconnected the battery for 15 minutes and reconnected
Read every troubleshooting guide online the internet please help!
I have seen the same problem posted everywhere but no solution
I have taken to dealership and they do not work on audio systems

Help help help I miss my bose system