Did you get a more detailed error message when trying to activate it in iTunes? Maybe the phone is blacklisted - where did your father get it for free? You may have to call Apple or bring it into a store if iTunes activation is not working after a full restore with the latest official ipsw.
My uncle got the iPhone from a coworker. My uncle has the shipping/packing slip and everything from the owner so it's not like it was stolen or anything.
As for the DFU mode, yes, followed the steps as stated on that site There isn't any Apple Stores here so going to one would be out of the question
There isn't any Apple Stores here so going to one would be out of the question 