Today I came across some great instruction sheet on how to downgrade your iPhone 4S (if you are running iOS 9.3.4 or lower) to iOS 6.1.3 with NO SHSH BLOBS required. Actually, the tutorial is extremely simple, it involves the the usage of a CFW (that you can also select to hacktivate (iCloud Bypass) if you don't have the original sim card or you are bypassed on 9.3.4).
The method apparently involves usage of Beehind tool made by Andrea Bentivegna which is basically a Downgrade CFW creator.
Now this is possible due to the Trident "Jailbreak" for iOS 9.3.4 and lower about which I made a video 2 days ago (You can check it down here), that's why it isn't working with iOS 9.3.5.
Unfortunately, when I decided to try this myself, I realized my iPhone 4S runs iOS 9.3.5 for some reason even tho I did not touch this device in over 6 months. What?! But guys on reddit.com/r/Jailbreak seem to got it working fairly easy.
Trident Jailbreak: https://goo.gl/7yW89R