Black screen on my S5?

[AC Question]

It seems like this is a common problem, since I've searched everywhere and found various methods, but they don't work. This all started after I updated to marshmallow back in early June (June 7th to be exact). About two weeks or so later, my phone screen wouldn't turn on, but the notification light, vibrations, and the glowing keys on the bottom seem to work. Sometimes I have to wait a few seconds to turn it on again, while other times (which has become often), I have to repeatedly press the power button until some luck happens.

I've done the smack method, the pinch method, wiping the cache, a reboot, taking out the battery and holding down the home button for a minute, etc. I really don't know what to do, so any help?