So I actually know what is happening here. A specific cable going from the mother board through the hinge without a light, to the top screen and speakers, is broken. This is caused by this cable being cut like scissors by the hinge. I cant really explain it well, but I know a You-Tuber who can explain it in detail and how to repair it. His link is here: https://www.youtube.com/watch?v=eAVDyIWg... There is also a part 1 where he takes apart the 3ds, but its not a 3ds xl, so i recommend using the guide to replace the upper screen that ifixit has, but don't replace the screen.