3gs iphone need help to restore

[vietkool]

Hi there,
My 3gs run at 3.0 at the time. then I accidently launch the fuzzy band and touched on the base band upgrade, after it flashing little bit then I turn off the power then I turn back on, the phone now show the cable arrow to the Itune. I try to restore with old firmware that I have download before 3.0, 3.1, and 3.1.3 but no luck at all.

1/4/2011
I just ran the upgrade to 4.2.1 from Itune. after it complete, reboot to a logo Itune with the usb cable and when I plug it in itune, there is a msg like this "The SIM card inserted in this Iphone does not appear to be supported" . What should I do next / how to unlock so I can make/receive calls ?

update
finishing 4.2.1 with Redsn0w method. then I add ultrasn0w to unlock after install ultrasn0w then reboot device but the phone keep on searching network ( 3G off)
firmware now 4.2.1 (8C148a)
modem 05.15.04

please anyone help