How do I restart / reboot the Apple Watch?
Like any computer, the Apple Watch will occasionally require a power cycle to correct problems. Resetting the Apple Watch with a reboot can be accomplished using a simple process.
Restarting Apple Watch requires a long press on the side button followed by a tap on the power button icon. Confirm shut down with a swipe on the display. Turn on the Apple Watch by holding the side button until the Apple logo appears.