All that's left between us and complete teardown glory is the sensor array, housed in the watch's back cover.

The four-sensor array includes infrared sensors, visible-light LEDS, and photosensors to track your heart rate throughout the day.

With the sensor assembly removed, we spy what we assume is the inductive charging coil left behind in the cover.

With the back cover removed, we get a glimpse of one last IC:

NXP Semiconductor Analog Front End Controller (likely)