Is it possible to remove an OTA update without the phone being rooted? Currently running software 3.17.651.1 710RD with Android 4.1.1. I want to rollback to the previous version of Android. I thought performing a factory reset would reset the phone to the exact state it was when I opened the box, but upon Googling it, it seems that software updates are retained after a reset. So how can I rollback my OS? Thanks.