Well I have an HD that isn't rooted, but I would imagine that the books would be in the same place. Download a file manager app like x-plore from the google play store. Then the files are under /sdcard/Android/data/com.amazon.kindle/files
You can use the app to copy those files into a place that is viewable from your computer when you plug the nook into it like /sdcard/My Files/Documents Or you can email it to yourself or something like that.