To remove the cover, insert the key into the lock if necessary and turn it to the unlocked position.
Squeeze the blue release latch and lift the cover off the system.
To remove the power supply, first disconnect the VRM power cable, Main power and VRM power cables and optical drive power cable, removing the cables from the cable harness as needed.
Next, remove the hard drive power cables.
Note that the hard drive power cable connectors are piggybacked on the SATA cables.
Remove the two internal power supply screws, and the four screws from the rear of the system.