Samsung Galaxy S5 black screen blue led light flashing

[AC Question]

yesterday tea time I put my phone on the side. Had about 50% battery. I noticed the front camera was up on the screen. I carried on making dinner for half hour. Went to use my phone and nothing was happening. The screen is off but there is a blue flashing notification light on. Is the phone off or on? It's been over 24 hours now. I'm thinking it's still on, so I'm waiting for the battery to die. Not sure how long this will take as if screen is not on then it's hardly using any battery. Don't know whether to charge phone and see if that helps or leave to run down. I've tried every combination with volume keys lock button and button etc nothin works.

Any help people would be great