Before powering on the VxRail nodes, be sure you have configured the networks, ports, and uplinks correctly.
After verifying the SmartFabric is configured correctly, power on the VxRail nodes. When the vCenter server appliance has had time to come up, connect to the vCenter server by FQDN or IP address in a browser and launch the vSphere Client.
If you cannot connect to the vCenter server, you might need to start it manually. In a browser, connect to the VxRail node where the vCenter server VM is located and power on the VM.