What does "pressure switch open with combustion air inducer energized" mean?

Answer

It means the electrical connection the pressure switch is supposed to "close" didn't and it being "open" won't allow electricity to pass to the next step so either the switch is bad or there is something preventing enough suction to make it "close". Could be a bad inducer or a blocked chimney but typically it is the switch. This would be the first thing I would check.