2g upgraded to 3.1.2 jailbroken now no signal
I got an iPhone 2g off Craigslist today and upgraded it to 3.1.2 through iTunes. After it was upgraded I jailbroke and activated the phone succsesfully. Wifi works, all apps work. However I have no signal bars. I installed ultrasn0w through cydia and now the phone says searching for a few minutes, then no service.
I then downgraded phone to 3.0 through iTunes and jailbroke and activated phone. Same result, no signal bars. Phone currently has version 3.0 and surfs web fine through wifi but no signal at all.
Someone please point me in the right direction. I am interested in baseband options, but do not know enough about baseband to fully believe this is the cause or I should start downloading programs to upgrade/downgrade.