2 second short flash = Getting GPS fix. This may be due to the device just being powered on/reset, checking for movement or sending a heartbeat.
2 second long flash = Device is in trip.
Constant on = Uploading data over LoRaWAN (this will only be a short period) or the config cable is connected (and talking to the app).
Constant fast flash = Invalid parameters or device requires a firmware update (please connect config app).