As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON DEPARTURE GOT PAX DOOR LATCH CAUTION MSG AT 6000' FELT & HEARD A RUMBLE AND THEN GOT PASSENGER DOOR WARNING MSG. COMPLIED W/QRH [EMERGENCY VEHICLES WERE ROLLED AS A PRECAUTION -- AIRCRAFT RETURNED TO BTR AFTER T/O]...FLT 5518 DEL 130 MINS