Great breakdown of info! So all I can do is narrow it down but this is how I'd proceed. First suspect, pressure switch. You can test with a voltmeter to make sure it's closing once igniter begins to glow. Or by jumping it out and see if it fires then. If not, check for flue blockage and listen to inducer to see if sounding slow or something in there. If not, could be gas valve. Test that voltage is coming to it. If not, I'd suspect the board. Keep in mind this is just a process, not a diagnosis. A voltmeter and knowledge of what you're doing with it is important. BE SAFE! Don't do anything you're not comfortable with.