Jaguar Car belt won't turn

i have a 2000 jaguar xjr supercharged and at first it kept telling me (abs) or something like that in the dash bored or (asb) and track not available so the next thing you now it says battery not charging so i open up the hood and the belt is not turning thus it overheat fast any ideas of what the problem might be i was thinking the alternator but would the alternator prevent the belt from turning? please help and it also makes noise as if something preventing it from turning!