i don't think knocking out will be necessary - is the plan still to take away his phone and say he'll get it back once he's done the community service thing? he could be reasoned with, even though he'll be a belligerent asshole about it at first. he downloaded chris' emergency button app and set it to report to near, and his thought would be that since he went radio silent for a few days before he was killed, one of the guard might use that to draw near out, which mello does not want.