I have an AO Smith FPSH 40 252 High-Efficiency gas water heater, about 14 years old. Today we had a power outage due to high winds and when the power came back on, the heater refuses to ignite. The blower comes on, the igniter starts to glow but never sparks - it shuts off with a click about a second after the gas comes on. It repeats this three times and shuts down. The green indicator light blinks six times, then pauses, which according to this indicates "System in lockout/Unit failed to light".
I have tried sanding the flame sensor and the perforated sheath covering the glowing element, as well as cleaning the rust off the little disc where the gas comes out. I have also tried "jiggling the harnesses" as one helpful forum user posted.
The gas is working fine. There are no obstructions in the vent pipe.
I should also note that I asked this possibly-related question about the same unit about a year and a half ago, so that might provide some additional background. The unit has been working fine, with cleaning of the disc and flame sensor about twice a year, up until today.
Do I need a new igniter assembly? Could today's blackout have caused the problem I am seeing? We had no blown breakers.
I really don't want to start purchasing parts without a clear understanding of the problem. Is there anything else I can try?