the machine should not be able to turn the heater on if there is not enough water in the drum so i am thinking poss board failure plus now the heater will be dead as well as it contains a fuse that may have blown
this fault seldom happens but it has to be investigated fully
on the really old machine before heater protection I have had heaters come on and start glowing red. then the heat toasted little brown marks on the washing to match the holes in the drum. Very dangerous days
Dave