Apc smart ups smt1500i doesn't turn on

Hi there, i'm a electric engineering,
i have a APC ups series SMT1500I but it doesn' turn on. I have try to replace the batteries with the same tipe,  but it not turn on. There isn't any visibile damage on the board, but i haven'y found the service manual-schematic drawings. 
there is someone who by chance has the wiring diagram - UPS service manual. thank you very much.