I was running FW 5.6.1.1 on my PW3, and I did a JB using the instructions here:
https://www.mobileread.com/forums/sho...d.php?t=265675
As that thread says, I had to upgrade to FW 5.6.5 first, because that JB exploits a "feature" exclusive to 5.6.5.
Though you have different hardware, you are running the same FW that I had, so that 5.6.5 JB should work for you too if you follow the step-by-step instructions at the thread linked above. Good luck!