Just recently I was approached by another sailor who was setting up their Iridium GO and it had stopped working.
He had tried “everything”. But thinking of it as a boat device, not a computer device, which it really is, he hadn’t thought of the obvious, Take the battery out and start again.
Iridiums are pretty reliable all told, but they are a computer and sometimes things will get beyond their limited ability to figure it out, in this case we suspect the SIM card was not fully locked in place and it resulted in a freeze of sorts.
This is a reason Iridium GO! is not accepted as part of GMDSS.
In fairness to the Iridium networks, the iridium GO is just as reliable as every other bit of technology on the boat and hundreds use it every year across the Atlantic without issues.
Also the Iridium network is GMDSS approved with a GMDSS approved terminal, which in Iridiums case would be the LT-3100S. But at over £4000 a pop its out of most private Yachties reach.