Ferroli Optima Boiler won't light and fan makes strange noise?

Our boiler's fan has been making some strange noises when kicking in for a few weeks now, a rapid clicking noise for a few seconds before it hits normal operating speed.

Yesterday, the heating and hot water went down. On checking the boiler, only the pilot light was on, yet system pressure was very low, about 0.2/0.3 bar.

I switched the system off, re-pressured the system and went for a relight, yet now the fan makes the rapid clicking noise continuously (for 10mins before I switched it off) AND the pilot light won't re-light.

Any advice welcome...

I have reasonable electrical/electronic knowledge but very little on plumbing and gas appliances.

cheers