Alternator belt

So with a squeal, if you pour water on it and the noise goes away, it is the belt (probably loose). If the noise does not go away, suspect a bearing. The fact it rolled means one of two things. 1. you have the belt in the wrong pulley (i.e. it is not straight). Belt alignment specs is something like 1/16"-1/8" per foot or something like that (used to teach this subject but its been a couple years). or 2. If you used a screw driver or equivalent to pry the belt onto the pulley, a belt can be damaged and if so it will roll like that. Oh, and although they sell belt dressing, none of the belt manufactures will recommend you use it.