Sounds like that shutdown the system, so the problem is just getting it to power off. You could try "halt -p”. That explicitly calls for the system to power off. If that doesn’t work, perhaps try “halt -verbose”, which will give a bunch of info on the next boot about what halt was doing, might show an error there that could you lead you in the right direction.
I would think it should be in the boot log, but I am unsure on that one.