electric stove

Question

In posts from previous years, you wrote that an electric stove could be turned off, raised and lowered on Yom Tov, but not turned on unless it went out by itself (I hope I understood correctly.) If it was on before Yom Tov, but turned off either because of excess heat in the kitchen, or for fear of leaving it unguarded overnight, could it be put on again? If not, how about by a gentile (shvut d'shvut)?