Accidentally restored my iPhone

[vietkool]

it exactly happened to me last 2 weeks ago, I have to use a redsn0w to put the phone in dfu mode then use iteun to point to a custom 4.2.1 to restore then after that use redsn0w again and this time point to a regular 4.2.1 to restore and install cydia. but my iphone is 3Gs I hope it the same step.

[g0tvtec]

So you are using a 4.2.1 firmware? Is that firmware possible to unlock and jailbreak on the 3G at the moment or do I have to downgrade it?

[vietkool]

I have to use redsn0w with the ipad baseband box checked then run the jailbreak then unlock with ultrasn0w.
here is the link you may want to read and follow instruction

http://www.iclarified.com/entry/index.php?enid=12949

[g0tvtec]

Thanks.

I am however stuck on step 2 as itunes will not let me restore anything. It just tells me I am using an invalid SIM card. I guess I will have to borrow somebody's SIM card. I remember being able to bypass this several times in the past when I had to jailbreak/unlock an iphone. Any ideas how to bypass this? I just remember accidentally doing it by experimentation.

EDIT: I was finally able to find out how to bypass this. You have to start itunes, connect iphone, hold down power AND home button until iphone turns off. When iphone turns off, release power button and keep holding down home button for another 10-15 sec. This will trigger itunes to allow you to restore your phone.

I was able to jailbreak and unlock it with Vietkool's instructions. Much thanks!