Blank MMI screen. Repaired power wires, screen still blank after repair.

[pmalloy90]

MMI screen went out a couple of weeks ago. Performed the common broken power wire repair as shown here (https://www.youtube.com/watch?v=3WXE-mifqXg), but my screen is still blank. Radio functions still working, just got a black screen.

I did some basic troubleshooting, and confirmed I've got 12.5V across the power and ground wires on the power connector to the screen, but oddly I'm only seeing 0.5V across passenger fuse A2 (https://fuse-box.info/audi/audi-a6-c7-4g-2012-2018-fuses#Fuse_box_diagram-2) (MMI screen power).

I'm curious if anyone has any thoughts or suggestions on what is wrong (or what I may have done wrong). I'm 99.9% sure I didn't cross the power wires going to/from the screen, so no idea how I'm getting power at the screen but not at the fuse. Tried finding a wiring diagram, but no luck. Not going to have a chance to take another look at this until Sunday, so hoping someone here can point me in the right direction between now and then.

Thanks!

[pmalloy90]

I just did some more thinking and realized there shouldn't be any voltage across the fuse, so ignore that comment.

[russjameson]

Check your radio module in your trunk!

I'll add more details to this later.
But I had the same issue, trouble shot everything. I ended up finally getting ahold of some wiring diagrams, and a fiber bypass tool off Amazon.
The culprit was in the left (drivers side) access panel my trunk. There are 2 control units there. The one you can see is the Bose amplifier for the entire car, it's the big one remove that one. Underneath that is a mount and in that is your radio control unit. All you need is a 10mm socket to get them out.
Mine got wet somehow and fried the fuse on the other side of the trunk underneath that storage cubby. I'll get you specifics, but I think it was C7 and a red 10amp fuse. Just check yours to see which is blown. I think on the fuse location diagram it was labeled improperly (socket) or something like that.
I bypassed the fiber plug wire, with the MOST bus fiber bypass plug, coming into the unit from the bus. And the screen immediately came up.
If this is the problem and you get a new radio module you will either 1. Have to take your car to the dealer to get it coded, or 2 there is also a chip you can desolder from your bad radio and add to the new one. It's a pain in the ass but it's doable.

I'll try to find pictures and more stuff when I get back home.