My question involves criminal law for the state of: Ohio

My 18 yo son was beaten by the police for supposedly resisting arrest. He was resisting apparently because they were charging him with underage consumption?!?! I don't quite understand why they would be arresting him if they were giving him a ticket for underage consumption. I thought that it was a misdemeanor crime and not one that would have you put into jail. I am not sure what his BAC was or anything at this point, but he claims that people where he was taken from took pictures of the cops slamming him repeatedly on the ground and dragging him and kicking him in the face. His right eye is so swollen with blood it looks like the eyelid is going to burst. He also had to get staples in his forehead from the assault. There were 2 full grown, adult male police officers that are well known in our small town, they are both over 6 feet tall and easily over 225 lbs or more a piece. My son turned 18 in December and they have told him over and over that they were just waiting on him to turn 18. They had a few confrontations in his juvenile past and my son has been known to be a smart mouth, but this has gone over and beyond what is necessary to restrain a foul mouthed kid. My son is not 6 foot tall and probably weighs 135 lbs. I just don't understand why 2 grown men who see it appropriate to beat a child to the point that my son was beaten. I just do not know what I should do if anything.
Thanks for any help or suggestions that anyone has to offer.
Heather