Reset sylvana motion and temperature zigbee

1. Remove the device from your smart home set up.
2. Remove the battery from your motion sensor, and leave it out for at least 6 seconds.
3. Locate the gray button on the left hand side of the sensor. Hold down this button while simultaneously re-inserting the battery.
4. Continue holding down the button for an additional 3 seconds until the light starts flashing blue, indicating that it has been reset and is in pairing mode.

Extracted from: https://www.smartplusforum.community/t/resetting-your-smart-motion-and-temperature-sensor/47   => You can watch a video too.