What was found
AIRCRAFT WAS GROUNDED: AFTER TAKE OFF AND FLAPS CLEARED UP WHILE CONDUCTING AFTER TAKE OFF CHECK LIST NOTICED THE #2 ENGINE FIRE EXTINGUISHING AGENT DISCHARGE LIGHT ON. ABOUT 30 SECONDS LATER AUTO F/LT A/THR OFF ECAM CAME ON. CREW DECLARED AN EMERGENCY AND RETURNED TO PHL WHERE THE AIRCRAFT LANDED SAFLEY WITHOUT FURTHER INCIDENT. WHILE TROUBLESHOOTING THE AUTO F/LT A/THR OFF ECAM MESSAGE MAINTENANCE ACCOMPLISHED TSM 73-20-00-810-985-A AND 22-31-00-810-812-A AND FOUND NO FAULTS OR DEFECTS. WHILE TROUBLESHOTTING THE #2 ENGINE FIRE EXTINGUISHING AGENT DISCHARGE LIGHT ON MAINTENANCE ACCOMPLISHED TSM 26-21-00-810-817-A AND REPLACED THE ENGINE / APU FIRE PANEL PER AMM 26-12-12. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED.