I just received my MacBook Pro Retina from repair today for a logic board replacement and I tested in the store and everything was fine with it. But because it's a brightly lit store, I wasn't able to check the backlight on the keyboard. Once I was at home I noticed the backlight doesn't turn on whatsoever and I called support, did all the necessary resets and to no avail. So I have to bring it back to the Apple Store unfortunately. I know the sensors work, but the lights simply don't. Could it be that they forgot to plug something in the logic board or is the logic board itself the issue? How does the backlight work (connections on the logic board to keyboard) anyone know?