I had this working Windows Server 2012 VM, that needed a reboot. After I rebooted the vm, changed some settings (attached a dvd drive), it would boot up again.
Now it says:
Failed - The attempted operation cannot be performed in the current state (Powered off).
I can't revert the setting, because of this state, I checked the host machine, tried booting it from there, but no luck. Also tried to reboot, reset, etc but nothing worked, it is not in the running VMs list.
I made changes to the VM using Remote Console (removed ISO from DVD). Received the same error. I had to un-register the VM, then re-register the VM and now it boots fine.