oh god. I just figured it out. This is kind of nasty actually.
So . . . root/vmware is the correct login. HOWEVER, I had already logged in successfully at some point, and had accidentally toggled to another tty terminal ( super/windows key on my keyboard does this ) and so I was seeing another login prompt. I guess since I was already logged in as root, it was rejecting my attempts to start a concurrent session for the root user without even asking for a password. Very tricky for the newbie, but I escaped with only 1.5 hours lost.
NOTE: this is on the vSphere Web Client's console . . . I suspect behavior could be different via other console tools.