3GS Jailbreaking to 4.1 fail

[d0rkster]

So I was jailbroken on 4.0 on the Iphone 3GS old bootrom. I decided to upgrade to 4.1.

So I followed these instructions

Preserve baseband/PwnageTool Method (Windows users):

Downloads:
1) PwnageTool made custom 4.1 ipsw
2) iTunes 10 and up
3) Redsn0w 0.9.6b2
4) stock 4.1 ipsw

Steps:
1) Find a custom 4.1 ipsw made by PwnageTool 4.1.2. You can either search the web, or if you know someone with a Mac have them build and send the custom fw to you. If you have a friend with a Mac, just borrow it and follow the above steps for Mac PwnageTool method.
2) Once you get a hold of a custom 4.1 firmware, open Redsn0w 0.9.6b2
3) browse to stock 4.1 ipsw (not the custom one)
4) Follow Redsn0w's timer to set device into DFU mode
5) open iTunes
6) shift + restore to the custom 4.1 ipsw made by PwnageTool

I did all this but I got an error. Now iTunes show n/a for software version and serial number and I am stuck on the itunes with the usb cord picture screen which I believe is the recovery mode. Every time I restart the iPhone, it goes back to that screen. I have no idea how to get out of this, can someone help me upgrade to 4.1 unlocked? Thank you

[Cowboy]

What error is it throwing at you?