Red Light Worcester 24i RSF combi boiler?

I left my best tape and the instructions on the wall when I drove off. They were gone when I got back. I have a constant red light on the panel of my boiler, and I dont know what it means. The boiler wont light for any reason, and I dont know why. New pump, new air vent valve, all else seems well. I suspect the gas valve, how is it purged? Thanks