Found the red thermal reset, but it didn't work. Then found the timer had got stuck when the problem started.The timer is located at the bottom left behind the kickboard on my BF50. Carefully rotated this to the STOP position (twelve o'clock), and then restarted - Hey Presto - it works again!
My root cause was a big leak from the bottom left of the door. Too much to be a seal, must have been the float switch that only allow the machine to fill the bottom of the tank, below the door (door seals only stop water coming round when it's spraying). I added a bunch of calgon-type tablets (and here's my faux pas) added boiling water to help the process. I must have tripped the thermal cut-off (which is set at 90degC according to the engineering sheet I found in the machine) and somehow tripped up the timer.
ScienceBoy, December 2011