Sime Friendly Format 100e not igniting

Pump runs and the fan runs only when you turn on a tap or the C.H. The green light (fan?) is on whether the fan is running or not. The boiler won't ignite. It won't attempt to ingnite even manually.
Had a mate down (Gas-safe boiler engineer) who has checked it all out. He's not 100% conversant with the model but seems to think it's the ignition circuit (housed in a blue box) As this isn't cheap and is non-returnable once opened, I'm hoping someone on here may have come across this one before.

Well the good thing is the boiler is responding to the call for heat and hot water so your pump and fan is running, are the parts that they are operating working though? speak to the engineer ask if he checked the venturi and air pressure switch, if the switch hadn't made typically the boiler wont light.

Pressure switch is good. We ran through his vault finder but we had a "no" when the only option they gave was "yes". The blue box ignition switch housing has a couple of marks from scorching which have corresponding minor marks on the circuit board. One has a light brown mark and there is a carbon "flash" deposit around a solder terminal on the board. As a spark from 25 years back these look to be the problems to me, but I'm way out of touch to start messing with the board.
My engineer mate has checked out everything else as fine except the ignition circiut and main PCB. He's no spark and I served my time with Edison!

Its very difficult for us to give you serious advice when we have not seen the boiler or this PCB with a carbon flash.

Its quite easy to measure the resistance between the component and the solder track but you dont seem to have done that or to have considered if it needs or could be resoldered.

Nor do we really know the capabilities of your friend. Its easy to do lots of irrelevant tests and that looks just the same as useful tests to anyone watching.

What conclusion has your friend come to ? After all he is the experienced one who was looking at the boiler.

I dont see much difference between him at work and him visiting you. How would he have dealt with the problem if he was at work?

Tony