who're you gonna pay to install one bolt? if you take it to a shop, you did all that work (like 98% of the alternator swap), and will probably end up paying a couple hundred bucks. I say leave it alone for a day or two, go back refreshed and give it another hour or two.
are you positive you didn't mix up the bolts in any way? did you try turning the bracket around as suggested? have you pulled it out and put it back in a couple times, or have you just been banging on it. the banging might've messed it up, I'd suggest getting another bolt from a dealership and trying that before resorting to taking it to a shop.
