As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAILED THREE START ATTEMPTS AT FL350 WITH FAULT LIGHT THAT REMAINED ILLUMINATED. GROUNDED - YES. ACCOMPLISHED B737-900 FIM 49-40 TASK 801 STEPS F AND H(1). REPLACED APU LUBE MODULE PER B737-900 AMM 49-91-11. INSTALLATION TEST PASSED. NO LEAKS.