Why is my iPhone stuck on the Apple logo?

In August, my iPhone 6s died. When I plugged it in stayed on the Apple logo for hours. I tried everything and even brought it out to try to turn it on again, today. It is still doing the same thing and refusing to turn on. I have searched up how to fix it on Google but all the results gave me is for when the iPhone is being updated. I have tried literally everything and would love to get my iPhone 6s back up and working. If you could get back to me that would be awesome! Thank you!