Hi Skandha,
I noticed the same problems when trying to upgrade from 3.9.4 to 3.9.7: Complete site including admin part becomes non-functional.
My site is still on WP 4.6.12.
Among other plugins, I am using “Multisite Language Switcher” and “Content Aware Sidebars”.
Have a look: http://www.st-ie.com
Like lesliekirk, I had to roll back to the previous version (3.9.4 in my case), which restored functionality.
Kind regards,
Ville