Every few months for 7yrs is a lot of opportunities to iterate on collecting field measurements. And it could be done in a holistic way that doesn’t break the safety certification.
This equipment was deployed in remote places without any kind of connectivity, sometimes not even cell coverage.
But the real problem is that the frequency of this failure in a single device was much lower than that. There were hundreds of these devices deployed and we never had one particular unit that was triggering all the time, sometimes here, sometimes there. Really a nightmare.