Hi and welcome to 2CarPros.
First, there is only one belt on the vehicle, a serpentine belt. It drives all accessories including the alternator and ac compressor. If the alternator wasn't an issue after he replaced it, chances are it should be fine unless he left something loose which could be binding the belt. Next, if the AC compressor clutch has locked up, it will both prevent the engine from turning and make a lot of squealing noise because the belt is trying to turn something it can't. The easiest thing to do in this case is to remove the serpentine belt and see if the car starts normally after doing that. If it does, then it confirms it is one of the belt driven accessories. And yes, I have seen situations where a locked up AC compressor clutch prevented the engine from turning with the starter.
With all of that in mind, first inspect the alternator to confirm it is still mounted properly and tight. If it is, remove the belt and see if you can turn the AC compressor pulley. If you can't, that's the problem.
As far as the battery drain, if the starter can't turn the engine but you keep trying, it will drain the battery quickly because of the added load.
I attached four pictures for you to see. Pictures 1, 2, and 3 show what is required to remove the belt. Picture 4 shows the AC compressor. Before you do this, I would recommend disconnecting the battery.
Let me know if any of this helps or if you have other questions.
Joe
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Sunday, February 17th, 2019 AT 5:56 PM