I would check in the trunk. Open the drivers side panel in the trunk, it will most likely be the top most module that has damage and but could be more. Using a T25 torx socket with a short 1/4 inch extension or possibly without, and a rachet remove the 3 screws, 2 facing the taillight and one facing the seats on the left side closer to the body. Pull the module out some and unplug all the connectors and optic plug and you will see right away it has water damage. At that point install the optic loop and turn the key on and the mmi should power up. Proceed to scan the car and see what other faults are stored.

-Cheers

Hi Sam!

Problem solved...for now and forever I hope!!

I checked in the trunk at driver side again. I didn't see the screws you where talking about, but I don't know if I have different layout or more basic equipment. Like I said earlier I only have the 4F0 035 056 A and small antenna.
But I tried your tip anyway and released the module and disconnected all plugs and reconnected the optical one... nothing happened...so I tried a few times more with no success.
So then I just assembled everything again and checked that all connections were right..and BOOM it worked....sounds odd and ridiculous but I think all went down on a bad connection....or I hope it was.

thanks again for all help!!
https://cimg4.ibsrv.net/gimg/www.aud...66affde884.jpg
This is how it looks.
I​​​​​​I think it was when I reconnected the big one it started up!!

have the same problem. in my case, it's the voice command module. i've pulled the fibre link out of the tuner and put that on the fibre optic bridge but what's the best way to get the tuner out of the car without taking all of the trim panels out of the back of the a6 avant in order to pull the module out of the radio? the dealership wants $3700 for the repair on a 2008 a6 avant.