my baxi boiler has failed to heat the radiators. I am not sure whether it s?

My baxi boiler has not heated the water or the radiators. Should there be a light? In the past I think I used to hear a nopsie as it it was lighting up. IF it is supposed to be alight please tell me where to look and how to re-light boiler.
the boler is FS 501 OF serial number 012756