iOS 10 to iOS 9 back track manual Update

I got screwed by the latest build of Xcode iOS 10. My program works great except that the layout is not conforming properly. For my layouts are completely screwed up.
So, I reinstalled Xcode Version 7.3.1 (7D1014) and I got everything working and now I am ready to start testing on my iPhone 6 Plus, except that I am running iOS 10.1.1 and I need to have my phone running iOS 9.

I did find an image file for iPhone7,1_9.0_13A344_Restore.ipsw , sadly it will not allow me to install it.

Alert 1
Error Alert

Sadly I have been doing all my backups by iCloud and I have never done a backup by iTunes.

AM I SCREWED? for trying to install a previous version ???

I did find this article on how to back track, but I have not been successful.
an article that I have found, but I am not successful to installing it.

Consider this case closed.
I am downloading Xcode 8.0, for this will let me finish up my project for release, by being able to run my project under iOS 10