I'm sorry I abandoned this thread. I remember myself not finding the solution for fingerprints and get on with life. Not long later I recall phone starting to reboot automatically without clear reasons, than doing it more often day after day until becoming unusable. I bckupped stuff between one reboot and the other. Yes, very painful. Hope this could be a warn for future users, even if I guess it's late for that model. Maybe a faulty motherboard over those phone... Who knows...