Battery drain after replacing MMI controls

Hey all,
I’ve had my '07 S6 for a few years now, and have been whittling away at the various issues. A few of the MMI control buttons either didn’t work, or were super sticky. I pulled out the circuit board, gave it my best careful cleaning, and once I reassembled everything it - the SETUP button doesn’t work. I hopped online and ordered a new circuit board. I installed it, and all buttons worked great, except the main control knob would scroll erratically. I removed the it and compared the two circuit boards and noticed that the original one only has 2 of the small black (I’m guessing optical?) sensors circling the center knob, but the aftermarket one had 6 of them - like seen here.

I ordered 3 or 4 more of these boards, eventually even forking over the $1,200 audi charges for the assembly (thankfully they let me return it), all with the same erratic knob issue. Eventually I stumbled on a board on aliexpress that matched the 2 black sensors that mine had (it says “no gps”, but I don’t ever use the navigation system anyways). I installed this one and everything seems to function fine, except now it seems to be draining my battery in a day or two.

Once I turn the car off, everything powers down, and after ~20 seconds, the MMI screen lights back up with the “S6” splash screen. The splash screen stays lit for 10 seconds or so, shuts off, and after another 10-20 seconds lights back up.

When I do a VCDS auto scan, it will show “0F - Digital Radio - - Status : Malfunction 0010”, but when I check the module for codes, it shows “No fault code found.” I’ve tried a lot of tinkering with it, all with no luck. My latest guess is that perhaps the control board is on a different firmware version than the rest of the system, so I’ve ordered the MMI update CDs and am waiting for those to get delivered.

Now that I’m thinking about it, I’m wondering if perhaps the lack of GPS is pissing off the navigation unit and now the navigation is keeping the system awake? Or perhaps the 6 sensor board would work, I just need a new knob that matches?

I know sticky/dead buttons are a common issue for these cars - has anyone else replaced the control board and run into similar issues?