Help needed, Iphone 3G wont work after jailbreak

Hello all,

My girlfriend has an iphone 3g that she had unlocked. A few weeks back she went ahead an updated the software and now the phone is no longer working.

The problem is when she updated the software I am assuming this broke the jaailbreaking software and the sim no longer worked, she went ahead and then re-set the phone to factory settings thinking this would resolve the problem, when it didnt she gave it to me.

So the issue I have is I cannot activate the iphone. I have a sim card installed but if I try and activate using just the phone it allows me to set the language connect to my wifi but then when I hit activate it takes about 3-4 minutes and then returns stating it cannot activate and I should try using Itunes. The iphone shows the connection to my wifi but does not show any network service.... it just says 'no service'

When I try and activate the phone using Itunes it takes about 3 minutes again and then says that no sim card is installed (even though one is)... just to note I went to Vodaphone and bought a new sim card and activated it (that didnt work), I have also tried using my own sim card for my current Iphone 4. (that didnt work either).

So to summarise, I cant activate using either the phone or Itunes.... can anyone offer some advice on how I can get this phone working again?.

Thanks

I have been doing some research on the net and it looks at though I need to either roll back the firmware or try a new jailbreak without a sim installed. Apparently I need to set the Iphone into DFU mode and can use a download from a company called RedSnow to perfrom the jailbreak.

Has anyone downloaded and successfully used RedSnow?.