i seen somewhere that you can force it to reset itself by causing it to overheat and the thermal cut off will cut in , then all you have to do is let it cool down and it will work again (until next time)

btw - to get it to overheat , switch it on so you light is on and wrap it up in a few blankets and leave for a hour or so then unwrap and let it cool down

don't know how true this is but it maybe worth a try