Chosen Solution
So I have tried to fix my screen, I don’t know if it can depend on me having place the logic board in the wrong place (screw in the wrong place and so on). This is what happens in the video. The screen works when I turn on the system, but as soon as I touch one of the keyboard keys or anything the screen goes crazy. I have attached an external monitor and everything works fine so is not the GPU. Brought it to Apple repair and said it was 850$ for the screen which is totally not worth it as I can find a used MacBook Pro retina Mid 2012 used for $500 Do you think there is anything I can try? Or is the screen broken? PS: Never experienced anything like this, it all started after I changed the battery and AC adapter (under the logic board), that’s why the question.
Lets assume you created the issue: I would make sure the iDP (eDP) cable was not pinched where it enters the hinge. Are you sure you put the screws in correctly? You may want to review the Logic board guide here MacBook Pro 15" Retina Display Mid 2012 Logic Board Replacement making sure you put the correct screws in the proper points as there are issues if you use the wrong screw where a short one is required. If I didn’t create the issue what is it? As we can see the horizontal and vertical banding leads me to believe the conversion logic which converts the iDP (eDP) single to the displays required scan lines (horizontal and vertical). Within the display assembly is a circuit board which does this (often called a T-CON board). I’m suspecting this is your real issue here. Sadly its not a part than can be replaced on its own. You really need a new display assembly MacBook Pro 15" Retina (Mid 2012-Early 2013) Display Assembly and here’s the guide MacBook Pro 15" Retina Display Mid 2012 Display Assembly Replacement
