As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NOSE DOOR OPEN RED MSG AFTER TAKE OFF. ACFT RETURNED TO BNA AFTER T/O, EMERGENCY DECLARED. FLT 4992 DEL 75 MINS. NC. FLT 4992 CX. FOUND CANNON PLUG LOOSE ON NLG DOOR SELECTOR VALVE. RESECURED IAW CRJ200 AMM 32-22-20. DOORS OPS CHECK NORMAL. ON GROUND WITH MTC SWITCH.