While not answering your slightly buried question, there's a solution which doesn't require digging around in an android file system.
I note you have a Nook Simple Touch, provided it's still working you'll just need two SD cards and you'll be all set. This will make the Nook download BN purchased books to the SD card rather than the internal and hidden partition.
http://nookworks.blogspot.com/2012/0...d-card-as.html