As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WOULD NOT PRESSURIZE IN AUTO MODE AFTER TAKEOFF. OUTFLOW VALVE WORKED NORMALLY IN MANUAL POSITION. FLIGHT RETURNED TO MSP AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED CABIN PRESSURE AMPLIFIER AND OUTFLOW VALVE ACTUATOR, OPERATIONAL CHECK NORMAL.