I'm the victim of gremlins. They're nefarious and sneaky. And they've foiled all of my attempts to move this project forward.
As I mentioned in my previous post, the NAGBox works perfectly on the breadboard. The LEDs do their thing, the buttons prompt a single response from the microcontroller, which in turn communicates with the Skywire cellular modem, and moments later I receive a text message telling me to call a specific loved one. It's wonderful, and I never tire of pushing the buttons and getting the messages, exactly how I designed it to work.
But then I transferred my design to a PCB and it all broke. Everything is hooked up (almost) exactly the same way as it is on the breadboard, except a bit more compact, and with a few connectors to make the button board detachable from the PCB. So it should work. But it doesn't. I've spent a lot of time troubleshooting, diagnosing and treating potential sources of issues, but still don't have a working prototype. So, I'm going to rebuild it from scratch.
Wish me luck.