Although Chinese junk is probably more prone to sticking than OEM, it occasionally happened 50 years ago. I'm sure your regulator is ruined and the generator tried to motor and couldn't so it got hot. I have even seen wire harnesses burn in a situation like this. I always check the Gen wire at the generator for voltage when I install a new regulator, but it can happen with a regulator that has been in service for a while. I recently had it happen on my 64 Farmall with a Delco regulator that had been in service quite a while. I haven't gotten around to figure out what all got hot and I'm not looking forward to finding out.