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.