As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GNDED. CREW WAS UNABLE PRESSURIZE ACFT DUE TO A VENT BLOWER FAULT & THE INLET VLV REMAINING OPEN AFTER OVERRIDING THE BLOWER. THE ACFT RETURNED WHERE IT LANDED SAFELY WITHOUT FURTHER. REPLACED THE AVIONIC EQUIPMENT VENTILATION COMPUTER & ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK IAW AMM 21-26-34-400-001-A & 21-26-00-710-001-A.