Make sure you are switched back to legacy Zwave (ZIP)
Try these endpoints
Do this first and reboot once it says it is already installed
http://YOUR.HUB.IP/hub/advanced/installZipgateway718 take a minute, and may need to run more than once, until you get already installed message.
Then these
http://YOUR.HUB.IP/hub/zwave/healthStatus - reports true or false
http://YOUR.HUB.IP/hub/zwaveVersion - reports zwave version or will time out if radio is offline
Report back on results.
If Radio is still offline then do a warranty claim Warranty – Hubitat Support