As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SUP - ETOPS SIGNIFICANT SYSTEM - AFTER LANDING 2 ATTEMPTS AT APU START UNSUCCESSFUL."APU FAULT" EICAS.//PERFORMED BITE ON ECU FAULTED REVERSE FLOW. REMOVED AND REPLACED APU CHECK VALVE PER FIM 49-11-00/101 AND INSTALLED VALVE PER AMM 36-11-11-404-008. NO LEAKS NOTED DURING OPS CHK. A/C OK FOR SERVICE.