What was found
IAH - FLIGHT 3407, DURING CLIMBOUT OF IAH THE CREW REPORTED AN EMERGENCY ELECTRICAL ABNORMAL TRANSFER CAUTION INDICATION, APU AUTO-SHUTDOWN IN FLIGHT, AND EMERGENCY LIGHTS ON. THE CREW RETURNED TO IAH WHERE THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED THE NUMBER TWO BATTERY SWITCH, OPERATIONAL CHECKED GOOD, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.