As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENGINE BLEED OFF AND LT PACK OFF DURING TAXI, ACFT RETURNED TO GATE AND MTX GROUNDED ACFT . MTX PERFORMED AN OPS CHECK OF AIR SUPPLY DISTRIBUTION SYS IAW AMM 36-11-00, NO MSGS SHOWN AT THIS TIME. OPS CHECKED GOOD. AIRCRAFT REMAINS NO ETOPS. MTX RETURNED ACFT TO SERVICE.