Server 2016 can ping but can't manage it remotely. (after removing GC role).

I was trying to replace a 2016 server with another server. While I was doing it, I remove Global Catalog role from the old server (running server 2016). Then, I had to get up to do something before I can demote (remove ad role from it). I was doing it remotely using RMM and splashtop. Now I can ping it from the new server but cannot remote into it nor manage it remotely. (Not from cmd, not from splashtop, RMM show server is down, and not from server manager).

Server Manager shows Error - Cannot manage the operating system of the target computer. I tried rebooting it with shutdown -i and shutdown -m but nothing works. Shutdown -i says failed to connect to registry and shutdown -m says error 53.

I added the GC role back to it but still getting error. I was able to see event viewer and saw that it was getting Kerberos error.

Can anyone help me?

Thanks,