Ideal HE18 flashing c

[gavski]

I have an Ideal icos HE18 boiler.
I drained the radiator system yesterday and now the boiler has a flashing c on the led screen but won't ignite.

Normally the c flashes during the ignition and then goes on full as does the boiler light, but now I hear the boiler try to light but then stops and the light and c continue to flash.

Could this be any thing to do with me draining the heating system (I was fitting a new raditor)?
Any Ideas appreciated.

[gavski]

Answering my own post but it may help anyone with similar problem.

After draining my heating system and re-filling, I bled all radiators but there was still air in the system and that was stopping the pump from working. There was a small bleed valve in the airing cupboard, and loads of air came out when I opened it, then my boiler fired up fine; phew!