Looping through Terms and Verify Google Account after hard reset
You will have to wait 72 hours, then try again and it will probably work. .. my guess is that you changed your google password, its a anti-theft thing that Lollipop 5.1 has.  anyways nothing you can do but wait for 3 days from the time you changed your google email password.  I had this same problem and figured out the reason after reading some threads.