That’s odd. If your Pi 0 is Online (Heartbeat only) indicates that device is unable to connect to the balenaCloud VPN (e.g. a firewall is blocking VPN traffic), and won’t be able to provide remote SSH connections.
Having said that during the last hours we had an API outage (read more on the status page) and some of my devices also had some similar issues.
Could you please check if your device is now online?
Could you please try to create a fleet, don’t deploy any release. Click Add Device, download the balenaOS and try to get the device only from that. Let me know if that works.