iPhone 3GS , iTunes Errors While Upgrading

[johnstank]

i have a 3gs (old bootrom) at 4.0.1 baseband, 5.13, unlocked and jailbroken, while trying to upgrade to 4.2.1, i created a custom ipsw with a bundle to keep the baseband i keep getting error 1600, ive looked every and cannot find a solution, any help would be appreciated (all my shsh are backed up in cydia)

[i.Annie]

Set it into pwned dfu mode with either Redsn0w or iReb before restoring to the custom firmware.

[johnstank]

no error but now it sits at preparing iphone for restore, and wont restore

[i.Annie]

So which method did you use to enter DFU

[johnstank]

Recovery mode, dfu mode, and pwned dfu and with the phone on.
The part when it gets stuck is in pwned dfu mode

[i.Annie]

Why are you setting it into recovery and normal dfu first? I was asking which tool you used to set it into pwned DFU

[johnstank]

Sorry redsn0w

[shanafan]

I created a custom 4.2.1 with PwnageTool and used Redsn0w to enter DFU mode. I was getting error 1600 in iTunes while trying to use PwnageTool to enter DFU mode.

[i.Annie]

Sorry redsn0w

Have you then tried to enter pwned DFU with redsn0w without all the other stuff you were doing before?