The Blossom Controller has shut down due to an error. The most common such error is lack of network connectivity for an extended period. A Blossom Controller that has been paired will try to reboot and connect again later.
Verify that your home network is up and running. Once you are confident the network is available, unplug the Blossom Controller, wait 30 seconds, and then plug it back in. That should clear the error condition.