As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE START CONTROL CABIN ZONE AMBER ON, DOES RESET WITH MASTER CAUTION. GROUNDED - YES. INTERROGATED PACK CONTROLLERS, FOUND NR 2 SHOWING FLIGHT DECK TRIM AIR VALVE FAULT REF B737-900 AMM 21-61-00. FAULT RESET WITH VERIFY RAN PACKS WITH NO FAULTS NOTED.