MMI screen replaced but not working

[JanP]

Old screen surface started to fall apart so bought replacement MMI pop up screen on eBay from a salvaged car. Part number matched all the way until last letter, mine had M, new screen had N, not sure what/if that means anything? I have a 2015, screen came from a 2016. 

The middle contact in the back is a bit different, white in original vs. black in the new replacement screen. Had to cut off tiny guiding "rail" to make it fit. Once powered up graphics were doubled above and below and very small, but it did work. Tried resetting screen but still the same. 

I then tried swapping the control boards between the screens to match the middle contact, but this time the screen was just black and didn't show anything.
The wide contact to the screen was a perfect match through and fell in place smoothly, so surprised nothing was showing.

Any ideas what it could be or something else that I could try out? 

[Steve Q]

I think the screen might need to be coded to the car.