As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PIT FLT 1557 EN ROUTE PIT TO CLT. AT FL 290, RECEIVED EICAS MESSAGE "FWD CABIN DOOR OPEN" PRESSURIZATION WAS NORMAL. HOWEVER, ONLY PARTIAL GREEN DOOR LOCK INDICATION. FOLLOWED QRH PROCEDURES AND RETURNED TO FIELD PIT. FLIGHT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE ACTION PENDING. AIRCRAFT CURRENTLY ON MEL. (A)