Dark/inverted colour top screen after replacement

So I recently bought a lot of 3 defective DSIs to repair and resell. I took both screens out of the worst one and put them in the others. The one with a replaced bottom screen works fine, however the one with a replaced top screen isn’t doing as well.

Initially I thought that it might just be the potentiometers that needed some tweaking. No luck there. Then I made sure all ribbon cables were snug which didn’t solve the problem either. Then I replaced the motherboard to no avail and now I’m out of ideas. I know for a fact that the screen I put in worked perfectly beforehand. If anyone has any tips feel free to share. Thanks in advance!