Solved! 6.0.0 Deep Sleep Problem

Solution
I am not referring to just 'stock' apps. Any app can keep a device from sleeping and drain your battery if it is set up incorrectly (or intentionally to do so) by its creators.
Have you checked the phones sleep settings? In "Settings" and then "Display".

You may also want to check if any app on the device is keeping it awake. There are many that will do that.
 


I checked the "Display" settings, "Sleep" is set to "After 15 seconds of inactivity".
About the apps that may keep the phone awake, the battery stats screenshots I posted is from "Safe Mode", only stock apps were running.
 
I am not referring to just 'stock' apps. Any app can keep a device from sleeping and drain your battery if it is set up incorrectly (or intentionally to do so) by its creators.
 
Solution


Yeah I got your point, what I'm trying to say is, it was on safe mode, so if it's an app problem it has to be a stock app because only stock apps are allowed to run in safe mode.
 
Ahh I see. Well if it is happening in "Safe Mode" as well, it could even be a hardware issue. If it is still under warranty, I would contact the manufacturer.