Saunier duval themaclassic f18e not working - the boiler started turning off showing a red warning light after a period of time, I would power the boiler down and it would do the same thing again. After getting by like this for a couple of the weeks the boiler won’t fire up now instead the red warning light comes on straight away. There are no warning codes on this boiler, has anybody seen this error before? Any advice would be great.

Thanks

Keith, July 2021