As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BUR - FLIGHT 2552, RECEIVED "APU SOV FAIL" CAUTION MESSAGE AFTER APU WAS SHUTDOWN. AFTER RUNNING ABNORMAL SHUTDOWN CHECKLIST, THE APU STARTED UP AND RAN OK. RETURNED TO GATE. MAINTENANCE REMOVED AND REPLACED APU FUEL FEED SHUT OFF VALVE ACTUATOR. OPERATIONAL CHECK GOOD. AIRCRAFT WAS RETURNED TO SERVICE.