I think I'm having a similar problem.
I think it is due to faulty circuit board.
If you take the front cover off (just bottom potion) and then when the boiler goes thru the sequence of sounding like it's going to fire up but doesn't, konck or bang the black box sitting on top of the circuit board at the same time it tries to fire up and see if that works. If it does then you need to change that part (number 407677).
H
January 2007