Worth reading in case it happens to you
I had nearly the same thing happen to me with a MacBook Air, except that I didn’t get all the expensive help they got, but I had driven an hour to an authorized repair shop.
After days of trying to figure out why my screen was “dead” I opened the laptop on the counter at the repair shop and the sun happened to be coming through the window at just the right angle that I could see the faint circle of my icon on the login screen. Fortunately I could click on it and log in without needing to be able to see it very well, and once I was logged in, I could fix the brightness.
Seems like a severe design flaw that this could still be happening.
Moral of the story: if your screen seems “dead” take your iPhone flashlight (or other light source) and shine it right up against the screen and make sure it isn’t just stuck at the login screen with the brightness dimmed all the way down.
I’m calling BS on this article… The owner of this computer created the issue by dimming the display when in clamshell mode. 9to5mac must be happy for all the clicks they are getting.
PRAM reset would have brought the brightness back on the screen. Replacing the MLB (main logic board) would have done the same thing.