As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THROUGH FL 34-35 NOTICED POPPING SOUND. CABIN WAS CLIMBING AT APPROXIMATELY 2000 FPM. COMPLETED CABIN ALTITUDE WARNING CHECK LIST, UNABLE TO CONTROL CABIN, COMMENCED EMERGENCY DESCENT. CABIN CLIMBED TO APPROXIMATELY 15,000 FT. REPLACED CABIN PRESSURE CONTROL MODULE. OPERATIONS CHECKED GOOD. REF: B737-300AMM 21-31-25.