The plastic frame is clipped inside the steel body with four clips, two each on the left and the right side of the watch, near the corners. You can stick a small screwdriver into the cutouts right above the clips and gently lever the plastic frame up, corner by corner.

Once the clips are released, use a pair of tweezers to grab onto the black plastic frame and remove the internal hardware.

Use tweezers or a plastic opening tool to disconnect the ribbon cable from the motherboard.