Why won't my watch vibrate?

First, confirm whether you've turned on the Do Not Disturb mode, and if so, please turn it off. Second, please go to the watch Setting-Vibration and check if you have toggled off the Alert/System vibrations.
If not, please try setting several alarms, and when it's time for the alarm to ring, please confirm whether the watch shows a screen on which the alarm rings but the watch doesn't vibrate. If that's the case, it will be difficult for us to determine it online. Please send your watch back to us for analysis.