As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING INITIAL CLIMB, CABIN PACK HOT. RAN CHECKLIST, THEN AIRCRAFT WOULD NOT PRESSURIZE. RETURN TO FIELD. LANDING UNEVENTFUL. REMOVED FROM SERVICE. R & R THE ECU IAW AMM 21-61-01-000+400-801. GROUND RAN, NO CABIN PACK HOT & AIRCRAFT PRESSURIZATION CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.