Fix ios5 Error 3002 - Update Error [Solved]

If you are getting Error Code 3002. Please do not panic. The ipsw file downloaded by you are Restore files. So instead of clicking on Shift + "Update" button on iTunes, click on Shift + "Restore" button. As shown in the screenshot below:

I faced this issue too. But Shift + "Restore" did the trick for me. Updated to ios5.