Need help downgrading my iPhone 3G to 3.1.x

[bimmeracer]

I am trying to download my iphone 3g back to 3.1.x software, but I keep getting the "the iphone could not be restored because the firmware file is not compatible" error. using http://www.techradar.com/news/phone...-to-downgrade-iphone-ios-4-to-os-3-1-3-704705
Could anyone help me?

 

[illpod.com]

We've used this method with success: link

Also shameless plug, apologies but thought it might be of use to you. If your in the UK we offer it as a send in service to take the hassle out of it for people having problems such as yourself.