As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU IS INOPERATIVE, NO IGNITION AND APU FAULT LIGHT ILLUMINATED AFTER START SWITCH ACTIVATION. GROUNDED - YES. REMOVED AND REPLACED IGNITER PLUG PER B737-900 AMM 49-41-51, AND REMOVED AND REPLACED IGNITER PLUG LEAD PER AMM 49-41-52. OPS CHECK GOOD.