iPhone 3G owners trying to upgrade to iOS 4 are reporting numerous issues with the update process, including updates that take hours and failed updates resulting in the sinister error 3002. Fortunately, though, there are ways to get around both by restoring your iPhone 3G instead of updating it.
If you are having problems with an iOS 4 update that is taking upwards of two hours to complete, the good news here is that the longest part of the update is actually backing up the existing media… a strange problem, given that you should automatically be backing up your iPhone 3G in iterative updates every time you sync. If you have a recent backup (and you should), a full restore to factory settings will eliminate the need to backup your iPhone 3G first, and should allow iTunes to update your handset to iOS 4.0 speedily.
The same is true if you’re getting error code 3002. Just click on your iPhone 3G under iTunes and click the “Restore” button. After the restore, you may have to reinstall some of your apps, but it should allow you to run iOS 4 on your iPhone 3G without any other problems or lost data.
Basically? If you’re having problems updating your iPhone or iPod Touch to iOS 4, do a “Restore” instead of an “Update.” If that doesn’t help, hit the comments, and maybe someone can help you..