What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO DFW TO ELECTRIC STAB TRIM NOSE DOWN INOPERATIVE IMMEDIATELY AFTER TAKEOFF. AUTO-THROTTLE DID NOT RESPOND. NO CAUTIONS OR WARNINGS. AIRCRAFT LANDED SAFELY AT DFW WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED HORIZONTAL STABILIZER TRIM CONTROL SYSTEM RELAY R850 (AALA202308044969). REPLACED AUTO-THROTTLE COMPUTER PER AMM 22-31-10. ACCOMPLISHED SATISFACTORY OPERATIONAL TESTS. (AALA202308046573)