2016 rMBP 15". Was fine previously. Ran on external monitor for a while. Opened it to look at a thing... There's a black line about 2/3 down the display. Not affected by resolution, not affected by GPU. Doesn't show up on external monitor, obviously. My guess is that a cable going to the display is loose, but it turns out they switched to special 5-pointed star bits to make it hard to look at things, and I have misplaced my Fancy Weird Screwdriver Bit Set, so I can't check to see whether it's trivial. Sooooo. I get to back up the drive, then take it to an apple place where they may or may not be able to repair it within a week, and if they have to do anything they may well swap the logic board, which indirectly results in loss of all data, because the data is soldered on. A+ customer experience, here.