As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAILED TO START TWICE WITH FAULT MESSAGE 49-41249 (START CONVERTER UNIT SHOWS LOW BATTERY POWER). GROUNDED - YES. PERFORMED B737-900 FIM 49-60 TASK 801 AND 822. APU STARTED NORMAL. GROUND VERIFICATION IS GOOD. NO CURRENT FAULT NOTED.