this is a software problem, not an ic problem. no soldering required. the wifi settings have been changed during the jb to those of an ipad.. restoring may solve the problem, but it will not change your baseband to what it was before unless your phone has bootloader version 5.8
what you will need to do is
a) download forecast from ireb's site- this will check your bootloader.
if you do have 5.8 then you can download fuzzyband from cydia and roll back to which ever baseband you had prior to the jailbreak
b) download the ios version you want...ie 4.1 from http://www.felixbruns.de/ipod/firmware
c) plug in to itunes and when chosing restore make sure you alt+restore and point at the new software (mac)
hopefully you'll have your phone back as it was before you decided to jailbreak!
if you are unfortunate enough to have bootloader 5.9 then you're stuck for a while.
you can try downgrading to 4.1. but it may not help