Top screen black but backlight working - where is the fault?

Hello! I have a New 2DS XL where the top screen is always black but the backlight comes on no problem. The bottom screen works perfectly for display and touch input so it doesn’t seem like there’s a full on connection issue somewhere, and I assumed that the top screen ribbon cable was just seated badly. I re-seated it (to the best of my knowledge) but the issues persist.

Replacing the entire top LCD might be beyond my skillset right now, so is there something that I’m overlooking that might cause the top screen’s backlight to work but not the display?