My Iphone won't turn on
I put my iPhone 4 in a bag and then put it in a locker in the gym, when i did it was at like 29%. I was there for about 2-3hours and when i came out and checked my phone, It wouldnt turn on. At first I thought it was out of battery because of the low battery it as already at but when i got home and plugged it in, The apple logo came up-- as if it was turning on. The apple logo disappears and I expect my lock scree to come up but it doessn't. I pressed the home button to see if it would come up then but it didn't. Then, after a minute of staring at my phone, the apple logo came up again, like it was turning on but it never did. It keeps doing it and I tried holding the lock screen button and the home button together to restart it but it didn't work.
I am freaking out here, please help!!
iPhone 4, iOS 7.1.2