Was Sold a Stolen iPhone 6

Is there any way I can Jail break or do something to make the iPhone I was sold work? When I try to set up my settings, after they ask for my Wi-Fi it say's I need to put in the current iCloud account but I don't know it because it was sold to me like that. I have no way to contact the seller. Is there anything I can do to unlock it, jailbreak it, or something?