2001 Daewoo Leganza Serpentine belt shredded

Hi my Serpentine belt shredded when my gf was driving and the car died. After removing the debree and replacing the belt the starter goes but it sounds like its not catching or something the pully turns but slowly. I took the belt off and all the pullys are good and the engine pully moves but slowly. The battery is good i checked it and i even replaced the starter thinking it went out but its the same thing. I cleaned all the connections and checked the fuses everything seems ok. Why won't my car turn over anymore. My gf said she disnt see it overheat when it died.