Same problem as other users here at this point. I screwed the casing a little, and it worked, but I like to do things properly.

If you want to fix it 1) open your computer.

2) the flex of the screen has a kind of little lock made on wire.

3) put the lock around the connection you should ear a little sound when it reach the good position. Make sure the tongue of the flex is above of the lock. And then it is fixed.

Wish it helps and sorry by my English.

Idk how to include photos