What was found
DURING CLIMB, LOST DU 1, 2, 3, 4, 6 & HAD NUMEROUS ALERTS, AUTOPILOT & AUTO THROTTLE DISCONNECT & NOT AVAILABLE. EMERGENCY POWER CAME ON. ACFT SEEMED TO BE POWERED BY EMERGENCY POWER ONLY, GEN 2 & 3 OPERATIONAL. GEN 1 DISCONNECTED. STARTED APU WITH NO CHANGES. RETURNED & LANDED WITHOUT INCIDENT. R & R EPCU IAW AMM 24-08-01-4, ER 15-05105, SWAPPED NR 2 & 3 GEN CTS. FOUND NR 3 GEN INSTALLED BACKWARDS. FOUND BATTERY 1 & 2 FUSES BLOWN. REPLACED IAW SWPM 20-31-00. DURING ENG RUN, GEN LOADS WERE 1-.8/2- .11/3.-.11. PERFORMED ERS 15-05105. CURRENT TRANSFORMER OPS CHECKED NORMAL IAW AMM 24-23-01-5. PERFORMED FUNCTION TEST OF GEN BUSS FAULT REST IAW MM 24-21-00-5. MX TEST FLIGHT, OPS CHECKED OK FOR SERVICE.