My iphone wont turn on at all, but when I plug it in to charge the apple logo will come on. Then after about 10-20 seconds the logo will just fade away. My computer doesnt recognize the device, and pressing the home button does nothing to turn it on. The only time the logo comes on is the first seconds after i plug it in to charge. I have read other threads recommending me to do things that require using the on/off top button but that button on my phone doesnt work. So I don't know what to do

PLEASE help
P.S i have a 3g. THANKS!
P.S i have a 3g. THANKS!