LED Flashing Fast Cyan on Electron w/AT&T SIM

[ScruffR]

I don't think Blynk uses the Particle cloud as transport, so you should be good without it.
If you don't use any of the Particle features (including OTA updates) you can opt for SYSTEM_MODE(SEMI_AUTOMATIC) (or MANUAL) and only call Cellular.connect() and wait for Cellular.ready() but currently you need to keep this issue in mind

How to handle Cellular connection loss on Electron

Have you tried this part of my post? I haven’t tried it out myself yet, but I could imagine that the propagation time of the !ready from the cellular modem to the micro controler might be too slow. How does your reconnect behave with this instead Cellular.off(); delay(500); Cellular.on(); Cellular.connect(); delay(500); Particle.process(); // explicitly trigger the background task if (!waitFor(Cellular.ready, 60000)) System.reset();