Though this method would only be useful if you’re stuck with a Locked iPhone or want to seriously run a random application but it has got some compatibility issues, this tutorial could solve your problem by demonstrating an easy way to downgrade your firmware.

Please note that this method is valid only for iPhone 2G and iPhone 3G. 3GS does not support this procedure.

1. Install the latest iTunes and then connect your iPhone to your PC or Mac.

2. Put your iPhone in DFU mode, this is how to do it:

• Turn off your iPhone
• Hold power and home together for 10 seconds exactly.
• Release power but keep holding home until the computers until a device is recognized at the PC.
• Now iTunes will detect your iPhone
• If the Restore Logo is present on the screen, you are in Recovery Mode, not DFU.

3. Once your iPhone is in DFU mode following message will be appeared in iTunes. Click on “OK” , Now hold Option key while clicking Restore in iTunes and browse the OS 3.1.2 or below firmware for your iPhone 2G, 3G. Now the restore process will take 10 – 15 minutes.

4. If you encountered an error message like 1011, 1013, 1015, just ignore them(Actually the firmware 3.0 is already successfully installed). Simply launch RedSn0w and do the Jailbreaking Unlocking process again. Check our guides on Jailbreaking iPhone here.

If you encountered with error message like 1601, 1602, 1600 or anything else then try putting the iPhone into DFU mode and try again.

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