iphone will not connect to itunes

Hi,

I have a 3gs iphone. My iphone won't turn on so I connected the usb to my macbook and my macbook didn't detect any sign of my iphone. I know it was fully charged when it turned off. I tried the power and home button for rebooting but no sign of power on. Then, I plugged my iphone into the power outlet and i finally got some sign. But then it tells me to connect to itunes and if i click info it tells me "Imei: unknown ICCID:unknown". Then when I unplug it from the power outlet to connect it to my macbook, the iphone turns off. What should I do? Thanks