Good point, it was a while back i forgot. Im almost sure that can only be the problem though! Unless his backlight isnt in the screen? It cant be the ribbon though, its unlikely, unless there is like a visible cut or something.
Itys a faulty screen. Replace the screen. The inverter should have done it, but if not, its cuz of the backlight, which is in your screen. Avoid trying to fix that yourself.