As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER TAKEOFF CREW RECEIVED A SERVICE DOOR CAUTION MESSAGE. THEY CIRCLED BACK AROUND TO LAND AT IAD. CREW SPOKE WITH MAINTENANCE UPON LANDING AND THE SERVICE DOOR INDICATION SYSTEM WAS PLACED ON MEL. AIRCRAFT DEPARTED WITH NO FURTHER ISSUES. SERVICE DOOR CAUTION MESSAGE AFTER T/O. SERVICE OUTER HANDLE UNLOCKED MESSAGE ON GROUND. PLACARDED AND PLACED ON MEL