chances are he blew the large fuse or fusible link that on the main wire going to the alternator. you have to take the links out to test them, they can look fine but still be melted inside the cover. if you have a voltmeter you can check the resistance with at least one side unplugged, should show 0 ohms. can also see if the largest wire to the alternator has 12v with car off, it should if the fuses and links are good