Went to work on a Trane 5-6 yr old TUA single stage with silicon nitride. Found a ignitor totally blown apart. I put in a new one and now I get a number 3 fault, which says a bad pressure switch. I confirmed that its ok and still get a #3. I returned with a new board and no more #3, but now I get a #9...Bad Ignitor. I get 15 ohms across the HSI. All voltages are correct zero volts across common. Upon start up I do get a very short amount of ignitor warm up but then after 1/2 to 1.5 seconds, the inducer shuts down and main blower turns on. This is on a new board. The inducer is running strong and the PS is not dropping out. I am thinking DOA board. Any input?