What was found
ON THE GROUND WHILE ON APU GOT STRONG BURNING SMELL, LOST ELEC POWER. WE SHUT DOWN APU. NO SMOKE OR FIRE INDICATION. T/S FOUND APU TERMINAL DAMAGED. RECIRC FANS AND E/E COMPARTMENT AND CABINS GALLEY OVEN COFFEEMAKER AND LAV HEATERS ALL CHKS GOOD. RAN BOTH ENGINES USING HUFFER CART AND PACKS. REPLACED BOTH RECIRC FILTERS PER B737 AMM 21-25. (LOG 8477818 - AIRCRAFT WAS GROUNDED).