Mi Door and Window Sensor 2 offline.

It the Mi Door and Window Sensor 2 fail to update firmware, please refer to the following steps:
1. Ensure that the sensor is within range of the Mi Control Hub and that there are no obstacles blocking the signal between them;
2. Try turning off the sensor and then turning it back on again. This can sometimes resolve temporary connectivity issues;
3. Restart the Mi Control Hub to refresh its connection with the sensor;
4. Make sure the battery in the sensor is not depleted. If it is, replace it with a new one;
5. If the sensor is still offline, try removing it from the Mi Home app and then re-pairing it with the app;
6. Ensure that both the sensor and the Mi Control Hub have the latest firmware updates installed;
7. If the issue persists, contact your local after-sales for further assistance regarding this issue.