... with so many sensors and computer chips in everything it could require a "reset". You should be able to do it yourself that doesn't mean it's designed that way. It's like the gas cap on my car, if I screw up the "three clicks" when I close it, I might have to pay my mechanic to reset the...
Could be some sort of "safety" connector that isn't, well, completing the electronic connection. If the door to the blower, on my old gas furnace, isn't on exactly flush then it won't turn on but the ignition won't click either.