With the Apple servers getting slammed, many people are having their devices locked with the spinning wheel. Essentially, these devices are bricked because they do not have a working operating system installed. Here is how to revert your device back to the old OS until the servers are running again.
So you tried to update to iOS 5, but now your device does not work at all. Here is how to force your phone (or iPad, etc) to revert to your backup.
1. Start the latest version of iTunes (10.5) on your computer.
2. Hard reset the phone by holding the sleep/wake button and the home button simultaneously until the phone restarts.
3. Then hold the home button down on the device and connect the usb cable to your device and to the computer running iTunes. Continue to hold the home button down through this entire process until the Connect to iTunes message appears.
4. iTunes will ask if you would like to restore the device. Click Restore and then select to Restore from Backup.
5. Now, wait a while before trying to update your system. Apple’s servers cannot keep up with the demand.