I have OSX 10.9.5, itunes 220.127.116.11 and iphone 6S with 11.0., which I'm really hating right now because of how the battery is draining so much, apps just freeze, phone retarts itself and the list goes on. Before I updated to 11.0.3 I did backup my IOS to 10.3.X ( cannot remember the last IOS I was on before I upgraded to IOS 11). Went online to see a few tutorials on how to downgrade from IOS 11 to 10.X.X by downloading IPSW file 10.3.3, 10.3.2 and 10.3.1 with no luck im stuck in itunes restore. I had my iphone plugged into itunes and I held down options key and click upgrade to select my IPSW file, which i picked 10.3.3. It extracted the file and look like it was going to update then itunes gave me a error of "iphone could not be updated, decline to authorize this image on this device for user". pretty much i have a brick phone. I dont want to restore it to IOS 11.0.3 im afraid ill permantely be stuck on ios 11 and cannot go back at all. anyone have any ideas? i saw this program called recboot but looks kind of shady. But then again a fresh install might do the trick of iphone6s acting up.