Returns the full status of the terminal identified by serial number. online reflects the terminal's own status as reported by PAXSTORE. payarcConnectOnline reflects whether the terminal currently has a live connection to the Payarc Connect platform (AWS IoT); it is true/false, or null when no connection event has been observed for the terminal yet. Device details (network, battery, model, firmware, IP) come from PAXSTORE; when the terminal is offline these are the last-known values as of lastSeenTime.