I had some recent problems with the battery on the latest cumulative of windows 10 mobile. So I wanted to restart fresh and I downgrad it to windows phone 8.1 . I forgot that now i can't update the phone to windows 10 mobile with windows insider app any more. Can someone give me a tutorial to how to get to windows 10 now ? My phone has an sd card , I read that you can if you have an sd card. Please help..