Note the temperature sensor has now been slid into the centre. (I also added a little more thermal paste but that may not be necessary).

With the boiler's temperature sensor in its designed position, the microprocessor can better control the system, so that it turns off the boiler when all the water has flowed out of the boiler into the teapot.

I'm guessing that, when the temperature sensor was assembled incorrectly, unexpected temperatures caused the boiler to turn off for safety reasons