This happened to me. Basically what happened was that I let the water collector in the bottom overfill and the water backs up a drainage pipe that fills it. After I emptied the water the light stayed on. This happened just inside the warranty but the engineer showed me that as the water level rises a float device triggers a microswitch in the back of the machine which stops the heater from working. Sometimes when the water empties the microswitch is left stuck in the high water position. It can be either freed and cleaned or replaced. Since then I empty the water after every use.
Hope this helps.
Wilf Arnold, January 2008
