If enough beacons have died such that it can no longer calculate it's position I bet it just stops. Should be a fairly easy thing to check just stop, send a not

If enough beacons have died such that it can no longer calculate it's position I bet it just stops. Should be a fairly easy thing to check just stop, send a notification, and power off or more likely since beacons are far more likely to die between runs just don't start if enough beacons aren't present.