Baxi boiler doesn't kick back in?

We had a leak on our boiler 2 weeks ago managed to stop it then got the plumber out to check it and do a service on it. Day after it stopped working properly, it wouldn't re-ignite, especially when using the hot tap. The plumber has since changed the following parts and still we have the same problem : igniter, lead ignition, flame sens electrode kit, ignition electrode kit, motor, thermastat box, diverter valve, NTC sensor and a PCD board. It makes all the right noises but doesn't kick back in and no error codes are showing.