A system upgrade failure on the Xiaomi Watch S4 can occur due to various reasons, such as insufficient battery, connectivity issues, or software conflicts.
To resolve this, please follow the steps below:
1. If the Mi Fitness APP or the watch shows an upgrade failure notification, try restarting the device and updating again;
2. Place the watch on the charger and ensure the battery level is above 20%, then attempt the update again;
3. Reset the watch, re-pair it with your phone, and try updating again;
4. Use a different phone to bind the watch and attempt the update;
5. If the upgrade fails and the watch cannot power on, please contact the local after-sales service center for further inspection.