updating iPhone 3g error 1015 can you help me about this?

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hi! im new in here i hope you can help me i update the iPhone 3g to 4.2.1 after downloading and installing it ses error 1015 so the iPhone do not open it is in restor mode how can i fix it can you pls help me heres my email its lanceroxas0908@gmail.com or at my skype its lance.roxas08 thanks hope to hear from all of you IOS users.