Skip to step #5 in the first post in the thread:
https://www.mobileread.com/forums/sh...d.php?t=313086
It is for the PW3, but step 5 and following are generic for firmware 5.x
(Except in step #7 you need to use an Oasis 2 firmware of any version greater than or equal 5.9.0.1, but you might want to stay below 5.10.x for now.)