I believe I read in a few articles that when your OS is Android 5.1 and you reset your gmail password prior to doing a factory reset/restore that your phone becomes "locked" for a period of 72 hours thus prevented you from completing the factory reset. I did exactly that yesterday and while I can get the phone to do the factory reset it will not proceed beyond the pages where you enter your last synced mail and password. Anyone else heard of this or experienced this?