Epson Apex 20020 - Manual (Page 118)

1. If the monitor is on top of the computer, disconnect it and
move it to one side. Disconnect the keyboard and any
peripherals and set them out of the way too. Turn the
computer around so that the back panel faces you.
2. As shown below, the top cover is secured by five screws on
the back panel and four screws on the side panels (two on
each side). Remove the screws and put them all safely to
one side.
3. Turn the computer around so the front panel faces you.
Hold on to the two sides of the cover and carefully pull it
straight toward you, away from the back of the computer, as
shown in the following illustration.