This article will help you if you encounter any of the following issues:
Sleep doesn't turn on
If the sensor is not inflating with a buzzing sound, it means that Data Hub is either out of range or disconnected. Make sure that Data Hub is plugged in and displays a green light. Then, if needed, try bringing Data Hub closer to Sleep.
Data Hub doesn't turn on
If the LED signal does not turn green after 10 minutes, plug Data Hub closer to a window, where the network reception may be better.