As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BZN - CREW RETURNED TO FIELD WHEN AFTER TAKE-OFF THE AIRCRAFT WOULD NOT PRESSURIZE. MAINTENANCE INSPECTED THE AIRCRAFT AND REPLACED THE CABIN PRESSURE CONTROLLER. OPERATIONAL CHECKS WERE PERFORMED AND CHECKED GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.