Does this MMI problem sound familiar to anyone?
 

2008 A6 has blank MMI screen...no radio, no Nav, no set-up menus; nothing. If I re-boot I get the 'AUDI MMI' start up graphic for a brief moment, then nothing.

The only fuse for the system that I could find is a 5 amp fuse in the trunk; it's OK. No spills in the MMI control panel, and all buttons work freely.

Can not get appointment for VAG-COM diagnosis for a week, so in the meantime I thought I would ask here...maybe someone has had the same scenario and can tell me what the fix is.

There's a 5amp fuse on the passenger side fuse panel. Look for the Communications fuse and check that for an issue

I had a similar problem and it turned out that my Bose amp had gotten wet and was no longer functioning.

Others have had similar problems when the Bluetooth module has gotten wet.

It seems that when one of the modules in the MOST loop go bad it prevents the system from booting up.

You can troubleshoot by disconnecting from each component and connecting a fiber optic loop which will bypass the defective component.

Right, after I started the thread I remembered that the MOST loop has to be intact or the screen goes dead. Tomorrow I will buy a fiber loop at the dealer and replace components one by one with the loop.

I would check your bose amp if it's not a fuse. That is one of the things I had to replace.

I'm only bringing this up because the same symptoms happened to me but because I inadvertently caused the problem I recovered very quickly. That is exactly what the screen looks like if you push the screen blanking button just above the glove box release. If the system just happens to be muted or turned down all the way then it gives the appearance that it's not working at all. I hope I haven't insulted anyone and for the record you're probably on the right track with the MOST loop.

Hey awdinut what happened with this? What was the issue?

just to help out anybody .... I had very very similar issue and it turned out to be the fiscon Bluetooth module mounted behind the indash changer in my q7 4L