How to Fix 1600 Error on a 3GS

1. Connect your iPhone to the computer through the USB cable that came with your iPhone.
2. Wait for iTunes to open, then click on the iPhone icon on the left side of the screen under 'Devices.'
3. Click on the 'Summary' tab and then 'Restore' from the options.
4. Click on the 'Backup' option from the prompt that appears.
5. Click the 'Restore' button. The restoration should take about 15 minutes to complete. The Apple logo will appear on the phone when it has cleared the error.