LG 60UH770V TV, Repair Help, Horizontal lines & Deinterlacing

[returnee]

Hello, I am trying to repair my 60UH770V but I am unsure what the problem is.

Symptoms:
- Several horizontal black lines running over the screen (that remain fixed in place and have no change whatsoever

- The lower 1/5th of the screen continually shifts between being deinterlaced and completely normal at a regular interval

So far I have identified that the tcon board is not the problem (had a spare one lying around) and that if only the right ribbon cable from the tcon board is connected, half the panel turns on in a steady white, while when the right ribbon cable is connected the other half of the screen is all over the place in the sense that white brightness is irregular all over that half and black lines run at regular intervals. Furthermore, once when the right ribbon cable was connected the other side of the screen had thick vertical pink lines running through it, so I think the panel is completely fine. I have placed tape on the left ribbon cable at different sections and if the screen turns on then the shifting with time is gone, however the entire screen is deinterlaced.

I would really appreciate any input on the matter, finding a new av board for this model is annoying at this point and I would prefer to hold off on that if possible.

Thanks for any help