iPhone 3G will not charge or sync

[NsOnLn]

I have replaced the cable, and tried multiple computers and I still can't get my 3G to charge or sync. I even replaced the port on the bottom of the phone and still no luck. Do you think its the motherboard? I was wondering if anyone had experienced this issue and what they did to fix it.

thanks

 

[yamabushi]

How old is the phone? Did you jailbreak the phone and install unauthorized software? Will the phone charge from the wall using a USB adapter plug? Does the phone still show anything on the display at all? Need more details.