I looked at how to hush it, and couldn't figure out how. My alarm was too high up to safely climb up and press the button -- I had paid for somebody to install it safely before.
So I called their support, and they told me they couldn't legally add a feature to turn it off. Which is a bit bewildering, considering that wave-to-hush had been a launch feature (albeit removed for apparent reliability issues). So I had to dangerously climb up high and remove the alarm and take out the battery.
But the worst thing? It never alerted my phone.
I have my own theories about why this happened. I had recovered my iPhone and not logged back into the Nest app, which I think is required for notifications to start flowing again.
But the support guy thought Nest engineering would be back in touch with me to discuss this crucial flaw within two weeks. Months later, I've not heard back.
Nest had a ton of options after the thermostat. It feels like they put a smaller B team on the smoke detector, despite it being a critically important safety device. It's really bewildering how the Protect turned out this way.
More generally, the lesson is that the Internet of Things is going to be fraught with complications.