Unfortunately, he should have listened to the first attorney. Now that he's convicted, the case can be appealed, but its always a long shot to win at appeal, especially when you've pled guilty to the charges and given a statement that said what you did that made you guilty, which is required in all pleas.
Unless he had ineffective assistance of counsel, there is little that's going to change that plea and conviction I'm afraid.
I'm very doubtful that you could change the violent crime to a non-violent crime. And I believe the other gentleman is correct in that it would require an appeal. My uncle John Dolan is a former prosecutor and an excellent attorney (not because he is my uncle). He is at (502) 905-0763. Please click on our website, it does not cost anything. Thank you.