I tried particle setup on my Mac to test the USB connection.
! Electron(s) cannot be setup via the CLI.
! We need to collect billing information, which we cannot do securely via the command line.
! Please visit https://setup.particle.io to setup your Electron.
Now the red LED near the battery adapter is on permanently.
The RGB LED breathes cyan.
You cannot set up an Electron from the Particle CLI. You need to use https://setup.particle.io or the mobile apps.
Once you’ve set up the Electron through the other means you can still use the CLI to flash code to it, for example, and do not need to set it up again.
The small red LED is the battery charging LED. It will stay on until the battery is fully charged.
I followed the instructions on https://docs.particle.io/guide/getting-started/connect/electron/ : “To check that your Electron can talk over USB, open a terminal and type particle setup.”
It does say this at the top:
It's worth noting here that you currently cannot set up an Electron from the command line (CLI) because we require that a credit card number be entered, but the CLI will be extremely useful for other things. Please use setup.particle.io or the mobile apps.