If your Xiaomi Watch S4 is not vibrating, please refer to the following steps to troubleshoot the issue:
1. Check whether the vibration alerts are enabled and confirm that Do Not Disturb mode is turned off;
2. If vibration alerts are enabled but the issue persists, restart the watch. After restarting, set multiple alarms and observe whether the watch vibrates when the alarm triggers;
3. If the alarms display notifications but the watch still does not vibrate, it can indicate a hardware issue. Please contact your local after-sales service center for professional inspection and assistance.