Remove three black 4mm screws.

Use guitar picks to dislodge 5 plastic latches around the perimeter (arrows)

There are two hidden plastic latches (arrows), one inside the hard drive slot, and the other between the floppy drive and the battery slot.

You may need to use a combination of a guitar pick and a spudger to dislodge the latch in the battery slot.

This step requires patience, sometimes latches can reconnect themselves, so you may want to leave the guitar picks in place until the cover is completely free.

Remove the cover and set it aside.