I recently shut the water supply to my combi boiler to fit a new shower (electric) and someone ran the hot water from a tap while the system was on. After finishing the job I turned the water back on and the boiler will not fire up for hot water or heating, you can hear it try then runs the pump for 2-3 minutes then nothing. Occasionally the pilot come red overheat LED lights up.

Any ideas?

RobertW, October 2015