To remove the power supply unit, unlatch and remove the system's base cover. Unlatch and remove the front bezel from the system. Identify the hard drive assembly and slide the tab to unlock the latch. Grasp the cables at the connector base and disconnect them. Lift the assembly up to remove it. Find the power supply unit and disconnect the two cables.
Remove the 2 screws and unlatch the unit to remove it from the system. To reinstall the power supply unit, place it back in the system. Relatch it and install the 3 screws. Reconnect the two cables. Place the assembly back in the system. Reconnect the cables and relatch the assembly. Place the front bezel and base cover on the device.