Unsure of process
I'm trying to understand this process better. I know if I had a 3G 3.13, I can restore using shift restore to 4.0 and then proceed with redsn0w. But is it the same if I have a 3GS new bootrom 3.1.3. Do I shift restore to 4.0 and then proceed with redsn0w? And Does updates update the bootrom ever? If I could understand the process better i could approach this with some confidence. Thanks.
New bootrom 3GS is decidedly different than how you'd do it with a 3G, but mostly in relation to new security measures Apple put in place to control which specific versions of firmware can be installed onto the device.
Couple of questions:
What firmware is the 3GS currently running?
Is it jailbroken? If so, what program was used to jailbreak it?
Do you have SHSH blobs for the 3GS for the 3.1.2 or 3.1.3 firmware?
(Are you aware of what SHSH blobs are and why you need them? If not, go here and read this: Caching Apple's Signature Server - Jay Freeman (saurik))
Let us know.