The iPod touch that I have came with 3.1.3 and when iOS 4 was announced I upgraded it to 4.1; that’s as far as I went . With the recent announcement of greenpoisOn’s untethered jailbreak for 4.2.1, I decided to upgrade the iPod.
Before upgrade
Backup via iTunes
1. As a rule of thumb always do a backup before messing around with the OS. Just connect the device to iTunes, right click on it and select “Back Up” and let iTunes do it’s magic.
If you have previously jailbreak your device and already have loads of apps installed via Cydia, make sure you backup that as well. There are several methods of doing so but the two easiest ones are via aptbackup or pkgbackup. Both can be downloaded via Cydia though please take note that pkgbackup is a paid app. Based on some of the forums I’ve been reading seems like pkgbackup is a more reliable solution though it’s still not a 100% guarantee.
New device or restore
2. After the backup, click on “Update” to download and install the new firmware.
3. Once the device is upgraded, iTunes will prompt to setup the device as new or restore from a backup, choose “Set Up A New ..” and continue, cancel the sync and eject the device.
4. Click here to download greenpois0n for MAC or WINDOWS. Save the file to your computer desktop.
5. Locate the file and open the application. You may need to extract/unzip the file.
just.yoga 