I figured out a way to get those unresponsive Xenons to reset and reconnect successfully after the Boron resets its network connection or is just power cycled.
Check the string of post starting with the one post linked below to see the code I used to reset the Xenons via software by using publish and subscribe functions that still seem to work even when the Xenons are flashing green.
Electron vs. Boron – “living on the edge” – what has changed with the cellular connection?