For Apple Watch, the force reboot trick is performed as follows:
- Press and hold down both side buttons on Apple Watch until you see the Apple logo
- The side buttons are the digital crown (the wheel), and the power button, both must be pressed and held simultaneously to forcibly restart the Apple Watch.
If you don’t hold them down long enough you’ll end up screenshotting Apple Watch instead, which is not what you want to do in this case.
Force restarting Apple Watch can be necessary to get features working again that have stopped out of the blue, the first time I had to do this was when the heartbeat BPM monitor randomly stopped working, and another time when the device screen became completely unresponsive for no obvious reason. Some of the causes which require a forced restart are almost certainly to be software related, meaning that maintaining updates of Watch OS software are sure to resolve issues that are bug related.