IBM 9009-22A Manual page 50

Figure 34. Closing the drive holder
f) Repeat steps "8.a" on page 33 through "8.e" on page 35 for the other drive.
9. Replace the backup power modules (BPM), if present. Otherwise, continue to the next step.
a) Unlock the BPM handle (B) by pressing the handle release latch (A) in the direction that is shown,
and pulling out the handle toward you. See the following figure.
36 Power Systems: Power Systems: Drive backplane