iPhone 3G will not turn on

Hi I need some help I just put a new back cover in my iPhone 3G I moved all the screws, the camara, power, ringer, battery all that is inside the iPhone cover to the other cover everything looks the same like in the old case I was wathching the video tutorial on how to do it but when I put everything and closed it the screen docent turn on when I plug it in I can hear it charging and my computer does recognize it. Before that I try to remove the digitizer but I was hitting it while trying to remove it and it left marks the ones that if you press the screen hard it leaves like a black mark with rainbow and deside not to so I just put the 3 first then the 2 second and the 1st third and close it then nothin happen then like I said I conected to the computer it sound like charging and my computer recognizite but that's all about it pleas help ASAP with any idea or you know how to fix it or know what I did wrong or something similar happen to you and know how to fix it.

Welcome to Mac-Forums

OK, next you shouldn't really be hearing the device charging, having the computer recognize the phone is a good thing indicating that at least the battery and the logic board are in some functioning order..

Did you touch the LCD digitizer at all? Is it possible it's dislodged so that you don't see anything but the phone is actually alive?

P.S, putting your questions in paragraphs makes it a LOT easier to read than a wall of text..

iPhone 3G

Thanks for the respond and the plastic opening tool touch the screen or digitizer know it has a black mark that kind of rainbow. I've try reconnecting the 1,2,3, againg put it in dfu mode but still won't work