i have a iPhone 3g that had a broke screen, replaced that and now it wont connect to iTunes or the computer.when i turn it on it boots to the iTunes logo with emergency calls only screen..it dont act like its charging ,but if the battery drains to nothing ,it shows the lightning bolt charging the battery till it boots than nothing. if i leave it off overnight it seems to charge but like i said it dont show it charging.. i have tried differant cords ,replaced the dock connector and put the motherboard in a known working phone all with the same results.. is there anyone that can give me some advice on what to try next please???