If you're interested in taking apart the top half, I've added some more steps. Otherwise, just replace your main board and put it back together.

On my second case, it had an issue preventing it from detecting if the top was opened or closed, presumably causing the battery to drain because it never went to sleep.

To get at the top section, remove the two screws on either side of the battery.

Next remove the screw holding cover for the LED and remove the cover. This step is probably optional.