Greenstar 30cdi boiler light?

I have a problem developed with my boiler - I am getting hot water, just no central heating. Only light that is on is the blue light, it is not flashing.
I have tried bleeding the radiators - there was a fair bit of air came out of several. The pressure indicator dropped right down and I have now boosted it back up. I have tried the reset button, other indicators flash but then nothing. Sounds like it is trying to start up a couple of times but again nothing happens.
Any help with this would be greatly appreciated.