how can i fix greenstar 30Si?

What does it mean? Can I sort this or do I need my engineer to come out? Is it safe? Or dangerous?

Just put in a couple of months ago - no problems till now just noticed radiators are cold - the blue light that's usually steady is on slow flash (mostly off, sometimes on) and the red "reset" light is flashing.

The thermostat is wireless and looks OK - it's signalling the little flame that means "firing" so the boiler should be burning.

What's the problem? thanks