Once the cover is off the drive and electronics just slips out by turning the case open side down, four screws behind the rubber vibration washers and you can unplug it.
Reassembly must be done exactly in reverse from a tilted position at the2 x usb plugs end. You will damage some clips, but I got mine back together ok.
Use a very small blade screwdriver to get into the gap between rear panel and the large cover that goes round the front and surrounds the 2 usb externals.
Starting at one edge force the tip of the screwdriver in and twist till you get a little gap, then unsert a larger screwdriver blade and twist till the clip pops off.
Move little screww driver to the other side of the bigger one and then move the larger screw driver pass the little one and twist etc
When you get past half way use two more screwdrivers to do the same around the corner where you started. Once you pop a clip around the corner leave the larger screwdriver in the gap and return to the end piece. (Doing the corner now helps stop the end clips slipping back into place.
Continue the end and then do two clips around the corner, then return to the other side and do two clips, then back to the other side and do two clips.
From here you should be able to do the rest with your hands by tilting the cover up.