Iphone 4 turned off and won't turn back on just over heats?

So yesturday I was on my phone as usual and it hadn't shown any signs of damage because I haven't done anything for it to be damaged its always in a case, never put it near water or anything but yesturday I looked away for 2 seconds look back at my phone and the screen just starts to slowly fade away lines were all down my screen and it faded from the top to the bottom, I switched it off quickly before it had reached the bottom and now it will not turn on, when I put it on charge I get no response from the phone but the top of the logic board near the camera heats up really hot like I can't touch it, it gets that hot buf only when on charge, can anybody tell me the problem and how i can fix it, I don't have the money to buy a brand new phone and I currently am stuck without a phone, I can't take it to apple because its out of warrenty and they will tell me I have to pay for a new one!

Take it to the apple store and they will replace it for free.