iPhone OS 4 GM is available for developers and it’s already leaked in the wild. If you downloaded those GM builds and now you want to go back to OS 3.1.3 or lower for whatever reason, we created a step by step guide for iPhone 3G and 3GS running on iOS 4 GM. iOS 4 is still in GM and you needn’t to edit your host files for iPhone 3GS to bypass Apple signatures.
Instructions to Downgrade iOS 4 GM
Step 1: Download and place OS 3.1.3 / 3/12 on your…
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