3g stuck on insert valid sim with no pin lock

[englishflavor]

I have a 3g that is stuck on the Insert Valid sim screen. Cant put in DFU or anything. I had a guy open it and says that it may need a new mainboard. Any fix for this or just replace the main board.

Thanks

[nebo1ss]

I have a 3g that is stuck on the Insert Valid sim screen. Cant put in DFU or anything. I had a guy open it and says that it may need a new mainboard. Any fix for this or just replace the main board.

Thanks

Need more information to even attempt to help. Are you using this phone on original carrier or have you JB and UL to use with different carrier? If different carrier how did you activate the phone?

[englishflavor]

When I got the phone it was on 4.01. I started to downgrade with Itunes to 3.1.3, used recboot, and then I believe that is when the error began. BTW, I have ATT so there should be no problem with my sim or need to hacktivate etc. The "insert valid sim" message is on the screen of the iphone and is the only thing listed on Itunes once you hook it up to a computer. I have tried two different computers and multiple usb cables. Any help is much appreciated.
Thanks!

Forgot to mention, currently this phone never made it to the RedSnow process as that was what I was going to do after activation.

[SKAMPERONE]

When I got the phone it was on 4.01. I started to downgrade with Itunes to 3.1.3, used recboot, and then I believe that is when the error began. BTW, I have ATT so there should be no problem with my sim or need to hacktivate etc. The "insert valid sim" message is on the screen of the iphone and is the only thing listed on Itunes once you hook it up to a computer. I have tried two different computers and multiple usb cables. Any help is much appreciated.
Thanks!

Forgot to mention, currently this phone never made it to the RedSnow process as that was what I was going to do after activation.

You need the "original sim card" that was on the phone when you first purchased it. Had the same problem with a friend who purchased the IPHONE in Canada and she had her original ROGERS SIM CARD. It worked, ITunes recognized it and then we UL to work with T-M in the U.S.A

[asma123]

Yeah more than likely your phone is not a usa phone. Since it's a 3g iphone I would suggest downgrading to 3.1.2 and blackra1n it.