As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE FROM BOI CLIMBING THROUGH 20,000 FEET LOST PRESSURIZATION. FLIGHT ATTENDANT HEARD LOUD NOISE COMING FROM CARGO AREA. RETURNED TO BOI. FOUND CARGO DOOR SEAL NOT SECURED. INSTALLED SEAL IAW MM 52-30-01. PRESSURIZATION CHECK OK. OK FOR SERVICE.