3GS wont restore to custom 4.2.1

[micksack]

hi all

I have been having this problem for the last few days with my friends 3gs.

He gave it to me on 3.1.3 not JB, so first thing i did was jailbreak it and made my life easier.

I then used redsn0w to put it into pDFU mode and then used itunes to restore it using a custom 3gs 4.2.1 firmware.

it seem to complete the process but when it displays to say your phone with reboot mine does not after the 10 secs but instead itunes detects it as a phone in restore mode and asked me to restore again. if i try again without pDFU mode it fails with error 1600. I have also tried to restore back to 3.1.3 but this also fails. I have tiny umbrella runing during all the restores if I do not it fails at the very begining when it trys to confirm restore with apple.

I was considering updating to custom 4.3 but I have heard ultrasn0w does not work with 4.3 is this right???

The phone is stuck in dfu mode all the time because when I try redsn0w to put it into PDFU mode it does not require me to hold the home and power buttons as you normally do.

There is no option to kick the device out of recovery in tiny umbrella so I really dont know what to do

Any ideas or help would be great or is there an eta on the 4.3 unlock

thanks

one thing i forgot to say is during the first time i used redsn0w i said it was an old boot 3gs and it failed so i redid redsn0w without a restore could this be the reason for all the trouble.I said it was old cause the serial number said to do so