Here's my progress on it (summary: no progress):
https://www.mobileread.com/forums/sho...d.php?t=151537
Amazon really stepped up their security. Our two big chances for hacking this thing is 1) luck (amazon forgetting to delete test scripts like on one guy's Kindle 3 last year) or 2) hardware modifications (to extract the OS files which we can use to analyze for exploits).