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How can I restore my ipad 2 wifi+3g gsm when I have removed the 3g module. It stops about midway when installing firmware and never finishes with an error (1). Maybe there is a chance to use it as an ipad wifi only?

No, you will need to put it back. Unless you replace the CPU and main flash from a wifi iPad so making it a true wifi-only model.

Yes u can use wifi only. But u must try fix logic board. U must terminate Some chip on logic board. And firmware update.