As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A/C DID NOT PRESSURIZE IN FLT RAN QRH AT 5000 MSL CABIN DIFF PRESSURE WOULD NOT EXCEED 0.3PSI. FOUND GROUND CONNECTION VALVE MISSING. PERFORMED BOROSCOPE AND FOUND THE BROKEN VALVE. R&R'D THE GROUND CONNECTION VALVE IAW AMM 21-22-04-400-801-A. PERFORMED PRESSURIZATION TEST GOOD IAW AMM 21-31-00-700-801-A. OK FOR SERVICE AT THIS TIME.