Under the bottom panel, I found a small circuit board handling the volume buttons underneath. Also, a linear slide potentiometer aligned with the lens housing. This probably measures IPD from the user’s mechanical adjustment.

Back on the top, since I had already cut into and ruined the skin, I just slashed it open. The battery was underneath this top panel. One top screw was in the center, plus one perpendicular screw on each side that doubled as case screws for the front cover.