As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRIOR TO DEPARTURE, THE R3 DOOR OPEN INDICATION ON THE EICAS DOOR PAGE. TROUBLESHOT IAW FIM 52-71, TASK 812-818. FOUND SWITCH DIRTY AND HAS EXCESSIVE SEALANT. REMOVED THE SEALANT AND DIRT AND LUBED THE SWITCH PLUNGER. CHECKED THE DOOR INDICTATION ON EICAS, ALL NORMAL.