Acer Altos R5250 - Manual (Page 50)

3 System upgrade 32
To install the top cover:
1 Perform the pre-installation instructions described on page 28.
2 Place the top cover on the chassis so that the tabs on the cover
align with the slots on the chassis.
3 Slide the top cover toward the front of the chassis until it is fully
closed (A).
4 Replace the screw on the top cover (B).