As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - ON TAXI FOR FLIGHT 2471 R PACK AUTOFAIL MSG ILLUMINATED. RETURNED TO THE GATE. DEFERRED IAW MEL REF 21-51-1B PLACARD NR 354579. AIRCRAFT RETURNED TO SERVICE. REPLACED NR 2 ACSC WITH NO HELP, MEL CONTINUED. REMOVED AND REPLACED NR 2 ACM I/A/W TASK 21-51-08-000-801-A01 AND 21-51-08-400-801-A01. OPERATIONAL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.