HP rp5800 Reference Manual page 43

18. Rotate the power supply back down to its normal position.
Figure 2-40
19. Replace the computer access panel.
20. If the computer was on a stand, replace the stand.
21. Reconnect the power cord and any external devices, then turn on the computer.
22. Lock any security devices that were disengaged when the access panel was removed.
ENWW
Lowering the Power Supply
Replacing the Riser Card 37