A little prying frees the battery easily. It’s great to see this common repair got prioritized, with a simple modular connector—no soldering required.

The battery is a 1.62 Wh (420 mAh at 3.85 V) Li-ion block which charges wirelessly.

In addition to the battery, the bottom part of the watch case bears a cable assembly with a tiny vibration motor, the heart rate and SpO2 sensor array, a barometric sensor, and a MEMS microphone.

Hiding behind the sensor board and peeking through the metal shield is a Texas Instruments AFE44l30 Biosensor Analog Front End module.