heatsink mainboard nut appears to have come detached

I've managed to save one logic board out of three. The problem here is the board layers have broken free and re-gluing is not easy!

The trick is to reglue the stud back down using some Cyanoacrylate glue. I've found the two part type works better than the straight glue.

The only way that seems to work is not the try to unscrew the heat sink but instead find a C clamp which can span across the logic board. Using a block of wood on the backside to protect the board and the components you'll then want to cut a block that will go across the band right where the screw is located. As you're putting a bit of pressure on the C clamp you'll want to make sure it does not shift or twist as you want pressure that is straight down.

Do a dry run so you're sure everything lines up. I waited to the last moment to apply the glue.

Let it set a good day untouched hopefully you can get it to hold. If not its time to look at getting a new board.