I managed to upgrade my 2G iPhone by mistake through iTunes to the latest firmware and now I can't use it at all because I'm using a SIM card from Europe and it wants me to put in a AT&T card (I guess?) which I don't have.

Is there any way I can get iTunes to work with my iPhone without a supported sim card? (or any other way) I just want to be able to use restore mode so I can use my WinPWN'd ipsw and get it all working again.

Help is very appreciated, thank you.