Samsung SM-G925F Power Key Jumper Solution
https://gsmfixer.blogspot.com/2016/02/samsung-sm-g925f-power-key-jumper.html
Samsung Galaxy S6 Edge G925F Power On Off Button Problem is due to the faulty power key or there may be missing point in power key ways to confirm that power button in working, if not replace the button and check.
If you did not get solution after changing power button then there should be an alternate repair solution which is given in the diagram given below. You have to apply jumpers as highlighted in the picture for Samsung SM-G925F ON OFF button problem solution.