To conserve battery power, Bluetooth connectivity only turns on intermittently, so no need to worry if it appears to be disconnected. This is completely normal.
If you do experience a Bluetooth connection issue when trying to update your plate, first confirm that the Reviver app was given Bluetooth permission. This is completed in the initial account setup and/or by going to the Bluetooth section of the settings menu on your smartphone.
If permissions are enabled, check to see if pairing was ever successful. If so, you may need to “forget device”, push the home button of the RPlate for 4 seconds, and repair within the Reviver app.