Why is my iPhone not working

Hey! guys

I had posted a question earlier on this site and was given many great answers, so thanks to all.

But, I have another problem now lol!

I replaced the lcd screen. I bought the complete kit. Now my iPhone will only turn on when it is plugged into the charger, and it only shows the little apple sign then it turns off. I reboot it and it tells me to plug it into itunes. When I unplug it the screen fades and will not come back. I plug it into the comp. and it dosent turn on, or anything errrrrrrgh! Please let me know! I only have power when it is plugged into the charger, but like I said not for long!

Tim!