how can i fix my baxi solo 2 40pf boiler? ii?

Hi,
I just changed the circuit board on my baxi, but it still wont light up.
The problem started when i noticed that when the hot water & heating wont light up together.
(Could it be the timer ST9400C ..??)

When turned on the lights show "Boiler & Fan" & there's a faint humming sound (fan maybe).

Any help would be nice.
Thanks for taking the time in advance.