Why is my galaxy s5 flashing and not wanting to turn on but when it does its fine?

[AC Question]

When my phone has been sitting inactive for a few minutes the screen will flash but not want to turn on. But once it does turn on its fine.

 

[B. Diddy]

Welcome to Android Central! This is when you press the Power or Home button to wake it from sleep? Does it happen in Safe Mode as well? https://support.t-mobile.com/docs/DOC-28456