Urgent iPhone 3Gs 3.1.2 new boot-rom problem

[kryX-orange]

Hey.
I have a iPhone 3G (S) with firmware 3.1.2 and the new boot-rom.
Also, I'm in need of unlocking my phone to use my sim card. Allthough I do own a sim card of the same operator to which my phone is locked (if that helps).
First off, i used blackra1n to JB my phone and also unlocked it successfully. After using it for about a day I wanted to download a new theme in Cydia. This requried a reboot, and this is where the trouble all began.
I knew that i had only a tethered JB, and I'm fine with that. But, like I've seen in many other threads, I got stuck in a recovery mode loop.

When trying to recover in iTunes, 3.1.3 had been released so i had to manually download 3.1.2 FW and try to update it. I got like a "not eligable to update"~ blablabla error message.
Tried both the Non-activaded and Activated custom FW's found on some page (I can look the home page up again if requested). I kept getting error 16xx (1640 if i remember correctly). So my final question is. What can I do to get my iPhone back on again? I don't care what it takes, just to get my phone back into a working unlocked state again?!

I was thinking that iTunes might accept a 3.1.3 custom firmware with the old baseband or w/e it's called, so that i can still unlock my phone. Suggestions?
Grateful for any reply!

[silverzz28]

anyone? I need this too!!!

[MadKillr05]

In Reply to both of you, Do your have your ECID's/SHSHs on file in Cydia? Also, whatever you do, DO NOT update to 3.1.3, it will kill your unlock