iphone 3G no network no service

hi there.
i need shematic for iphone 3g in order to repair network issues. besides the iphone was already opened by someone else. any suggetions to solve this problem plz
regards

I know this was a while ago, but did you have any luck repairing the network issues?
A friend of mine has an iphone from which everything is still working except the connection to the network after he had dropped the phone.