My boyfriend had a warrant from a failure to see his probation officer, but he turned hisself in so what could possibly happen??

Much of that is at the discretion of the Probation officer and supervisor handling your boyfriend's case. It is a good thing that he turned himself in, however, for the purposes of sentencing. I recommend that he hire a Public Defender, or that you contact the local bar association for a lawyer referral.  Good luck.