What was found
AIRCRAFT RETURNED TO PLATFORM DUE TO DURING BOTH ENGINES START, THE ALT MODE AND CDS FAULT LIGHTS TURNED ON AT BOTH DISPLAYS. MAINTENANCE PERSONNEL PERFORMED REVISION, DETECTING THE FAILURE CODES 31-68081 IN THE DEU. THE BITE TO BOTH EEC WAS PERFORMED IAW FIM 31-63 TASK 807 PROCEDURE, NO CONFIRMING FAILURE, TESTED CORRECT.