I upgraded from 4.4 to 5.1 using the .img file (within the .rar file). Loaded that to a USB drive, installed via external port. Used the Software Upgrade app (in your My Apps folder) and was lollipop loaded in ~10 minutes. Jarvis 16.1 auto loads so you'll need to log into your Play Store & update Kodi to 17.1 (another 5 minutes). Then this "newbie" spent a little time reloading my preferred sources & such, a few "live streaming" tweaks and I'm up & streaming fine.
If this analogdog can do it, it can't be that tough. Have at err