Forgive me if this has been mentioned. I could not find it in a search. There are reports of lock failure of some inReach units leading to at least one SAR response.

Early Report
http://packrafting.org/forums/viewtopic.php?f=31&t=5732

Roman Dial site
https://packrafting.blogspot.com/2017/09/inreach-fail.html

Garmin Response
https://andrewskurka.com/2017/garmin-responds-faulty-sos-lock-button-inreach-se-explorer/