Help jailbreaking 3.0 (downgrade from 3.1.2)

Ok, so Im jailbreaking my friends iPhone, which is currently on 3.1.2. I tried to restore using custom 3.1.2 I made on my mac, but it got stuck at connect to iTunes screen, and after hours managed to get it out of that screen by jailbreaking 3.0 with redsn0w. So the phone is working now, except it has no service, and won’t connect to wifi. Any help? Is it possible that the 3.1.2 baseband update isn’t compatible with the 3.0 firmware?
Answer #1
3.1.2 + blackra1n
It honestly doesn’t get any easier than that.
Answer #2
Yeah just figured that lol. Not used to windows, I have mac at home. Cheers anyway bud.