HP ProOne 400 G1 All-in-One Hardware Reference Manual page 48

15. Rotate the bottom edge of the access panel down (2) and press it firmly onto the chassis until it
locks into place.
You will hear audible clicks as the latches click into place.
Figure 2-48
16. Place the computer in the upright position.
17. Reconnect the power cord and external devices.
18. Lock any security devices that were disengaged when the access panel was removed.
19. Turn on the computer.
42 Chapter 2 Hardware repair and upgrade
Replacing the access panel