I am posting llinks on how to upgrade and downgrade from ios5. Tried it on the 3gs and worked like a charm. P.S no developer account needed.
Manually restore to the iOS5 beta firmware. To do this, open up itunes and select your iPhone from the sidebar. Hold down the shift key and press the restore button, iTunes will ask you to locate the firmware file, point it towards the firmware file which you’ve downloaded above. Once the restore is complete follow these steps the activate the phone.
Read more: How to Activate and Update to iOS5 Beta 1 Without a Developer Account on iPhone 3GS/4 ot iPod Touch | TechDeville
To downgrade:
Step One
Download the respective firmware file for your iDevice and place it on the desktop.
Connect you iDevice to your PC and place it into DFU mode. To place your device into DFU mode:
1. Turn your device off.
2. Hold the power button for Three seconds
3. Without letting go of the power button, press the home button. Keep them pressed for 10 seconds.
4. Let go of the power button and hold the home button until your PC detects the phone. It takes upto 30 seconds.
It may take several tries to get your phone into DFU mode
Read more: How to Downgrade from iOS 5 Beta 1 to iOS4.3.3 on iPhone3GS/4/iPod/iPad | TechDeville
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