My iPhone 4 Wont Turn On

I got this iPhone 4 just a day ago but it wasen't charged. I started charging it to see if it would turn on but it didnt turn on at all ! I thought that was strange so i tried out another charger but still it wouldnt turn on at all ! I have tried charging it for 3 hours and nothing happened. Like I connected it and it said it was charging but it would never charge or turn on so im not sure what I can do. Do I need to get a new battery or something ? Please help !