IBM Power System 9040-MR9 Manual page 56

Figure 42. System backplane screw locations
b) Grasp the system backplane by the front (A) or middle (B) metal bulkheads and the rear metal
bulkhead (C). Lift straight up to disengage the four alignment pins from the bottom of the chassis.
Figure 43. Grasping the system backplane and disengaging the pins
c) Place the system backplane on an appropriate ESD surface.
42 Power Systems: System backplane