As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 3817 -ATB/PRESS- RETURNED DUE TO CABIN ALT WARNING LIGHT AND HORN ACTIVATED AFTER TAKEOFF. CORRECTIVE ACTION: PERFORMED LT-RT DCPC BITE CHECK PER B737 AMM. LAST FLIGHT SHOWED LO-INFLO. TEST SHOWED NO FAULTS. OPS CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.