As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ATTEMPTED T/C NG 49, EO 03483 1 "NG APU ECU SOFTWARE UPDATE TO VERSION 5". UPDATED FAILED SOFTWARE, LOCKED UP AND WON'T RESET APU IS NOW INOPERATIVE DUE TO APU ECU LOCKED UP. ACFT GROUNDED. R & R APU ECU & OPS CHECKED GOOD REF AMM 49-61-12.