Manually updating ipod
DO NOT INTERFERE with the device when it is being updated, doing so may mess up the update.
When finished, the i Phone, i Pad, or i Pod touch will reboot itself automatically and enter the i OS 9 setup screens.
i OS 4.0 final build is live now but it may take some time for i Tunes to offer i OS 4.0 update for your i Phone & i Pod Touch. Now once i Tunes starts click on your i Phone/i Pod Touch from devices list3. Now browse & select downloaded i OS 4.0 firmware and click on Open5. Apple doesn't release updates to the operating system that powers the i Pod as often as it does for the i Phone.That makes sense; fewer i Pods are sold these days and new models come out less frequently, so there are fewer changes to make.Using a firmware file offers little benefit to the average user and simply complicates an otherwise easy update process.
This will update a device running a prior version of i OS to i OS 9, as described here it will perform a software update, it does not restore or reset the device.After it's been restored, then you can update the operating system.