What is going on witbh my galaxy s4?

[AC Question]

So, as I have always done before, I would have my phone sitting on the counter in the bathroom while I shower, that way I can listen to music. I got out of the shower and I saw that my phone was already unlocked and so I went ahead and checked me messages and when I hit the button to put my phone back to sleep, it didn't work. I then thought to myself that I should just take the battery out and put it back in like I always do when my phone freezes up. I took the battery out and put it back in and nothing happened, excpt the screen will come up and say ''samsung galaxy s4" then go back off. I tried putting it on the charger and the battery pops up and then disappears. My phone does this Everytime I do either one. I know it's not the battery because my battery works in my brother's s4. Can you please tell me what you think happened?

 

[meattray]

Hold volume up down and power button all at once. Should reset the phone.