Quote from Patrick Mast:
Be careful. There are 2 LONG screws and 2 short ones. Mark which got out where as the short ones do not fit in the long wholes.
I found one long screw. It goes in the corner right next to the fan.
Also, I would recommend taking the audio cable off nearest to the cd drive and not on the audio board. It's easier to see if it is lined up when reconnecting it.