Did you use something such as a fire rated silicone to seal the new inducer motor and did you tighten it very well? I've never had an issue with any baffle (not even certain what you mean by that) when changing inducer motors.
Are we sure that your heat exchanger is not cracked? If so that would be the foremost reasoning why there's no pressure.
Are we sure that your heat exchanger is not cracked? If so that would be the foremost reasoning why there's no pressure.