Re-Install 3.1.2 Firmware on 3.1.2 Iphone 3Gs Stuck in Recovery Mode with no SHSH
I made a very foolish mistake. I took an iPhone 3Gs with 3.1.2 and wanted to jailbreak it using redsn0w. When it came to picking whether it was an old or new bootrom, i went ahead with old as it was a week 41 iPhone. Well, turns out the phone would not reboot, so I am now assuming it is actually a new bootrom and I would have to do a full restore 3.1.2 as per the instructions.
Now the phone is stuck in recovery mode with all black screen. Trying to reset/reboot the phone by holding power/home does absolutely nothing.
I want to go back to 3.1.2 or upgrade to 3.1.3, 4.0 or 4.0.1 but I do not have the SHSH for any of those firmwares. I am not downgrading, but I still can't get Apple to sign the firmwares. I even tried restoring with a custom Pwned 3.1.2 firmware, but that did not work either; just got an error 1600.
Can I do anything here or is my only option to upgrade to 4.1 and just wait for the jailbreak/unlock?
If it helps, I am able to go into System Profile and get my 16 digit ECID code, unfortunately, tinyumbrella is not picking up the iphone as it is in DFU mode and I am tehrefore unable to create any SHSH for it.