Secure the PCB to the upper case half using the original 5.38 mm #1 Phillips screw and the included washer.

Peel the white back off the thermal pad, being careful not to accidentally peel the thermal pad off of the heat sink.

Set the heat sink onto the voltage regulator so that their lower left corners, as oriented in the third picture, are aligned. Press the heat sink firmly onto the voltage regulator to ensure that it will stick.