What is causing my screen to not turn off after the established time?
You can use Wakelock Detector to find out what app is causing the behaviour. Remember to read the correct procedure from the app's info:


  How to use:
  
  1 Install the app 
  
  2 Charge your phone above 90% and unplug cable (or just reboot the phone)
  
  3 Give it a time (1-2 hours) to accumulate some wakelock usage statistics
  
  4 Run “Wakelock Detector”, it will display wakelock statistics for you!
  
  5 Check the apps on the top, if they show very long wakelock usage time then you found the cause of your battery drain!
  
  *Note: Wakelock Statistics are gathered since Step#3