Hey, I had the same issue on Macbook Pro 15" late 2013. I unscrewed the bottom case, disconnected the display ribbon cable, reconnected it and the problem went away! In my case, the problem started after a heavy object fell on my laptop (ouch) so maybe it was the impact of the collision that moved the cable. It's worth mentioning that the cable seemed to be seated just fine on its connector, but apparently it wasn't. TL;DR: Disconnect and reconnect the display cable.