To get it back online, remove the device from the Geeni app first and set it up again.
You can follow the steps below.
How to remove the device:
1. From the main device list, select the device which you want to remove.
2. Click on the (...) button on the top right corner. Scroll down until you see "Remove Device".
3. Tap on "Remove and clear data" and then "Confirm"