I got hold of a 3DS where the top screen constantly flickers. I already tried to reseat the ribbon cable but that didn't help. When displaying colors like red or green or black the screen doesn't flicker. But with white the flicker is most extrem. When using the 1200K screen filter option from Rosalina menu the flickering will also stop.
Here a link to a short video that will show the problem.
http://wiiucodes.ddnss.eu/verschiedenes/Top_screen_flicker.mp4
Here a link to a short video that will show the problem.
http://wiiucodes.ddnss.eu/verschiedenes/Top_screen_flicker.mp4