I received notice of update last night. During update, phone froze - showed black screen, red triangle, exclamation point - No command. Have been trying for hours to get to screen to do a reset. As last resort, attempted factory reset. Now phone is in a loop from "Erasing" to the white screen with "powered by Android." I can't send it in for repair as I can't be without it that long. Can any one help, please? Phone is not rooted, is all stock, is on Marshmallow.