Problem:
The root password we have as default is not working from SSH but able to log in through IPMI (DCUI).
Were there multiple failed login attempts?
Have you tried disabling lockdown mode and enabling SSH to to connect. If not please try.
Steps are as following in this article.
There are few options from lowest order of difficulty if above does not work.
1. Try disabling the SSH and restart management agents and try to log in again. Hope this helps. The IPMI is accessible for customer from customer portal as well.
2. Refer to
Steps to reset a lost or forgotten root password of an ESX/ESXi host(https://kb.vmware.com/s/article/1317898).
OS cannot be reloaded for VCS. So resetting through Host profiles is the next option. This works out in most of the cases.
3. Finally, this might be extreme resort to delete the host and order a new one.
Hope this helps and let us know if you have any questions.