My two screws are the same diameter - 1.1mm, taking a Philips PH000 driver. However the one toward the middle is 3.3mm long, the one nearer the side is 2.2mm long.
Mark all cable connectors with a spot of white correction fluid before removal. This will remove the risk, when reinserting them later, of getting them the wrong way round. Yes - I know they will only plug in one way round, but it does make life easier if you are not in perfect lighting!