glow worm 18si, do i need a new pcb at €480 +?

hi. my boiler is just over 2 years old with very little use so far. ive had this f5 fault for the last few months and each time i reset it, but now there is no power to the pcb. bord gais reakon i need a new " mother board " at a cost of €480 plus labour charge. has anyone needed to replace there pcb or could it be maybe a fuse that has gone?
thanks
thanks