I had some problems updating my Kindle to version 5.1. I had to uninstall most of the hacks in order to avoid error 006. After updating I received the dreaded "Your kindle needs service. Contact Amazon support" screen. After connecting it to the PC the problem disappeared but the repair needed screen came back at every restart and various other occasions. I managed to Reset my Kindle and now it works fine.
My problem is the fact that I uninstalled the jailbreak prior to the update and now I can't jailbreak it again. I believe that the after the update my kindle ignores the data.tar.gz file.