Q: iPhone 5s and iOS 9.3.5 battery drain

Like the last time an unwanted update happened, i forgot to remove the update software

to disable the daily update messages and bang, i was taken from 9.2x to 9.3.5 in 10 minutes.

I've been enjoying fantastic battery life with 9.2x -   After 9.3.5 install, and including turning

off anything and everything except essential features - I've seen this battery life drain from

100% to 84% in 1-hour - thats not 'doing' anything at all with the phone - just having the

screen unlocked and open to the display of various items contained on the phone.  Yes,

everything i can think of (which i would like to keep on..) i've turned off.  After unlocking

the screen - literally In a minute, I just saw the percentage drop to 83%. 

So i guess i have to permanently leave it in battery saver mode..? How can i get back to 9.2--

unofficially if necessary -   i JUST DON'T GET THE POINT OF THIS INCONVENIENCE.

Sorry.. i-Rage… In my case thus far, OS 9.3.5I quite *****…literally.  I want to be a fan

but you are making it a challenge.  Any advice?  Is this widespread?  Well known issue?

I haven't been scouring the web about this or anything but i sure as F--- am seeing instant

poor battery life with this accidental update