I had a situation recently where a number of live migrations failed in a truly nasty way. The live migration failed part way through, but didn’t properly back-out the changes. This left the instance running nowhere, but in a “migrate” state in the database. I tried to reboot the instance, which then left the instance in the “running” state.
Of course, the instance wasn’t actually running anywhere and the reboot command wouldn’t start the instance, because it thought it was running. The logs complained that the instance wasn’t running whether I tried to restart the migration, or reboot. What a full of fail situation.