A device sends its data to the Hub and the Hub sends the data to the cloud. When you don't see any sensor data in the dashboard there can be something wrong with the connection from the device to the Hub or with the connection from the Hub to the cloud.
First, you need to be sure that the Hub is working correctly. Therefore, read this article first. If you are sure the Hub is working, continue with the following steps:
Doublecheck the serial number of the device. You can see the serial number in the dashboard and on the back of the device if you remove the backplate. Make sure that the "offline" device in the dashboard is also the one you have in your hands.
Wave with your hand in front of the device. A Wave-device should show a glowing ring, a View-device should switch screens. If the device does not react, the batteries are probably empty. Please plug in new batteries and try again.
If the device is alive, but not connected to a Hub, it probably has a bad connection to a Hub. Bring the device close to a Hub, take out all the batteries, and plug them back in. Give it some time and normally the device will connect to the Hub. You can also see on the dashboard how good the connection is/was with the Hub.
You see the connection to the Hub in the device overview:
The number in the red square shows the connection with the Hub.
Between 0 and -85 dBm: good connection
Lower than -85: This can cause dropouts in the connection from the device to the Hub.
When you bring a device closer to a Hub, we recommend restarting the device (take out all the batteries and plug them back in). When a device is restarted, it will search and connect with the closest Hub.