Is 3G service down today?

[ScruffR]

@BobG

It would also be nice to be able to read the state indicated by the color LED remotely, so that we can understand what has happened without having to have someone on site to observe the device.

That would somehow be tricky since remote requires an active connection which was not present at that time, as I understood.
Howeverthere already is a solution available: Watchdog.
It's not remotely triggerable, but is a means for a devices to monitor itself via inbuilt hardware.

You might like to have a look at this implementation of @rickkas7

Electron sample code for fault tolerance and problem debugging

Most of the time the Electron just works, happily connecting and disconnecting from the cellular network and all is good. Except once in a while, some devices have a hard time getting reconnected. Disconnecting the battery and power usually solves the problem, but that can be a pain for remote devices. This experiment is some code that might help recover from this situation automatically, and also log some data to better figure out what’s actually happening, so if it’s a bug, it can just be fix…

BTW, in addition to @bko's possible ways to impact cell reconnection in your own code, there are also some less "esoteric" ways. When using SYSTEM_MODE(SEMI_AUTOMATIC) or SYSTEM_MODE() manual a lot of the Cellular.xxxx() and Particle.xxxx() functions can interfere when used "wrong".