Looking at the specs for a Garmin inReach Explorer (assuming that is what he has), the battery life is said to be 30 days when set to 30 min interval reporting. Ryan left on December 4 and it seems plausible that with such long battery life he just forgot about it and his battery just crapped out yesterday on Jan 1. At least that is what I hope has happened and he is already happily tied off to a dock in NYC.