S5 Black screen+blue light+vibrate

I have a Galaxy S5 that doesn't really turn on. When you press the power button a blue light pulses on the top left corner of the screen, and it starts quietly vibrating every 10 seconds or so.

I have tried taking out the battery, and holding down the power button and that didn't work. I have tried doing that and then plugging it in letting it fully charge, but it still does the same thing. I have tried pressing the power and volume down button, and that doesn't do anything either.

Any suggestions as to what could fix it? Thanks!