Remove both expansion bay modules using the levers on the front of the computer.
Insert your index fingers inside the expansion bays and search for the two ribbed tabs on the underside of the upper case. The tabs are located near the bottom corners of the keyboard.
Pull the tabs toward yourself and the keyboard will pop up.
Slide a spudger downward between each plastic strain relief cable and the wall of the case in order to bow out the cable beyond the small tab holding it in place.
Once the strain relief cables are free, lift the keyboard off.
Grasp the upper case near the back left corner and lift up partly so that you can access and disconnect the audio in/out cable from the sound card in the upper right corner of the case.
Be careful not to lift the upper casing too far before you have disconnected the audio in/out cable.
Remove the upper casing. Note that there are two tabs on the laptop's front that often cause the upper case to stick.
Remove the single T8 Torx screw from the front left corner of the PMU.
Lift up the front edge of the PMU and disconnect the three smaller orange ribbon cables (two on the left side of the large PMU cable, and one on the right side) that attach to the underside of the PMU from the upper case.