What was found
CREW REPORTED-LG AIR GND FAIL EICAS MESSAGE AFTER TAKEOFF. USED DN LOCK REL TO RAISE GEAR. MULTIPLE AURAL WARNINGS. TRIPLE CHIME, FLAPS, LANDING GEAR, TRIM. AURAL WARNINGS CONTINUED. RAN QRH. DETERMINED SAFEST OPTION TO RETURN TO DAL. HAD NORMAL BRAKING AND STEERING. IDLE STOP FAIL. PRESSURIZATION THINKS STILL IN THE AIR. GOT STICK SHAKER AT TAXI STOP. MX TROUBLESHOT TO BAD NLG DOWNLOCK PROX SWITCH