Original post by: Albert ,
Trying to check the screen cable to ensure it is completely seated inside its port on the main board. Then check the screen again. Its possible the cable came slightly loose and could theoretically cause that effect. Top screen ribbon cable can be weathered from all the opening and closing. If the ribbon cable's loose for the top screen, if it's actually ripped instead of loose, you may need to order a new top screen or a new DS.