It would be a good if you go through the logs and get the exact issue why its failed to start.
but the possible reason would be VMware KB: Attempting to reconnect an ESXi host that appears as Disconnected in vCenter Server fails with the error:…
Well. I got a little further. My mobo has a Realtek 8168 nic which is not supported by ESXi 6. I updated the driver, so now I can see the NIC becomes alive (I can ping it). But the error still remains. I also removed the server from the vCenter cluster, no result so far. Is there a way to get access to the vpxa.log file of the failed ESXi install?
Assuming you can SSH to the device ?
the log would be in /var/log/
if you can't ssh do you have access to the console ?
If so you can f2, then view system logs, then 5 VirtualCenter Agent.