As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CRUISING AT FL390, A LOUD THUD & BANG WAS HEARD BY THE COPILOT AND PILOT. IMMEDIATELY NOTICED THE CABIN VSI PEGGED AT 6000 FPM. EMERGENCY DESCENDED TO 10000 FT. ATC DECLARED AN EMERGENCY AND THE ACFT TURNED BACK. COULD NOT GET THE CABIN IN AUTO NOR MANUAL MODE.