It is above the Proximity Sensor and through there you can insert your screwdriver.

There is barely any documentation on the HMD which makes repairs an incredible pain.

There is an opening towards the screw if you space out the lenses, You'll need a decently long screwdriver to get to it.

I skipped putting back on the clamps since they were tedious to put on, Instead i just screwed the heatsink screws in and hoped that would keep it tight.

Why in the world is this thing so tightly connected?