What was found
AIRCRAFT WAS GROUNDED: EVACUATION HORN WENT OFF RIGHT AFTER V1. CUTOFF BUTTON DID NOT WORK. MAINTENANCE PROCEDURES SUGGESTED DID NOT WORK. QUICK REFERENCE HANDBOOK PROCEDURES FOR RESET NOT APPLICABLE. AIRCRAFT RETURNED TO DFW. HORN WAS STILL GOING ON AT GATE. UNABLE TO SHUT IT OFF. COULD NOT TALK ON PA OR CABIN INTERPHONE. AFTER EXTERNAL POWER WENT OFF, IT FINALLY SHUT OFF. REMOVED AND REPLACED CIDS DIRECTOR #1 (AALA202104189013) AND #2 (AALA202104209014). ACCOMPLISHED ALL TESTS. ALL TESTS PASSED. AMM 23-73-00.