how can i fix my baxi bahama 100 boiler?

ive replaced both flow switches also all electrodes .it fires up ok for weeks then it dosent fire up at all the orange neon light flashes on then goes off but boiler dosent light somtimes in the morning it fires up no problem when u try it a little later it dosent fire up ive left it off went to work came back home and try it again it fires up no problem iam confused