Jailbroken iPhone upgraded to 3.1.2. - Sim Card not supported. PLEASE HELP! :(

[kwokymonster]

Hello, guys. I'm one of those losers who upgrade my jailbroken iPhone to 3.1.2.
I had a iPod Touch with Installous, then my parents gave me an iPhone 1G. It was version 1.1.2. I think and it was jailbroken.
So my friend told me to restore and update to 3.1.2. because I wanted to get Installous on my iPhone.
And now it says the SIM Card in this iPhone is not supported and the iPhone's got that iTunes icon and USB wire sign with the slide for emergency thingy.
Anyways, I've been reading around on the forums and some people were having the same problems.
One Person fixed it by downgrading to 3.0, but I can't seem to downgrade.

Any instructions on solving this problem is GREATLY appreciated. Thank you.

 

[goodkat]

1-get blackra1n
2-use blackra1n to jb
3-install bootneuter from cydia, use bootneuter to unlock, re-boot
4-install afc2add from cydia, re-boot
5-get diskaid or iFunBox
6-use diskaid or iFunBox , goto root>private>var>root>library
7-find a folder call : lockdown
8-backup lockdown folder to your pc
9-delete lockdown folder, re-boot