Why does my Samsung S4 keeps booting up and then restarts itself?

[DanSmith45]

So I recently updated my Samsung Galaxy S4 from Kitkat to Lollipop, it was working until my phone was overheating for a little while so I turned it off. When I turned it back on, all it does is the boot up animation, then it shows my lock screen, before I can do anything, it will restart itself again. I don't know what to do, because even going into safe mode still causes the same problem to happen again. Can you please help me, thank you.