It's windows vCenter or VCSA? Did you checked the logs?
is zaCPTRPVC01 resolvable by your DNS server from the workstation where you deployed the new appliance from in Stage 1? That's most likely to be your issue
try these solutions:
- “could not connect to one or more vCenter Server Systems:https://vCenterFQDN:443/sdk” error in the vSphere Web Client (2…
- VMware Knowledge Base
Can you resume the installation from here?
Open your preferred browser and type the address https://IPAddress_DNS_VCSA:5480 and select the Set up vCenter Server Appliance option.
If its a Windows vCenter then upgrade will not roll back to previous version as it failed during firstboot. You need to revert back to snapshot or restore from backup.
If the source vCenter is Appliance, you can power off the failed Appliance and turn the source vCenter back online.