KindleBreak is one of the easiest jailbeaks to install.
https://www.mobileread.com/forums/sh...d.php?t=338268
You would have to upgrade to at least 5.10.3 through as high as 5.13.3 except 5.12.2.2.2 which should not be installed. I can never remember or describe how to get a specific old firmware version, but quite a few people at mobileread can.
if you don't like 5.10.3 compared to earlier firmware, you can then downgrade to a lower version. 5.9.6 added some nice features.