[Sepelion]

So, I decided to play around some more, and successfully ended up jailbreaking a PW3 wifi 2015, which previously got bricked (along with a few other people in this thread with the same PW3 wifi, so there's some snag somewhere).

Here's what I did:

1.) Attempted methods in OP, got to step 4. I originally had 5.8.1.1 (the latest PW3 firmware)
2.) Upon attempting to update with the factory initial firmware, it just looped a lot and then came up with the repair screen. Bricked!
3.) Connected via USB while looping/failing install, and my windows 10 machine did let me access the root directory as Kindle, with just a documents folder and nothing else.
4.) in that root directory, made DO_FACTORY_RESTORE blank file (common unbricking method)
5.) eject
6.) hold down power for 10-15 seconds until the light on the bottom changes to the orange/restart or whatever (I'm not actually sure if this step was necessary, since it was looping in some sort of reboot after the repair needed screen -> power button anyways, so it inevitably gets to the DO_FACTORY_RESTORE command)
7.) that returned me to the setup screen, and device info confirmed 5.6.1.1, HOWEVER, that's not the initial firmware, that's consumer release, and I verified this by attempting the next step of installing the JB file in root and trying the ;installHtml in search, only to have it do absolutely nothing.
8.) Okay... my next thought was let's put that initial 5.6.1.1 from the pastebin back on the root directory. Do that, and the update button in settings is active, hit update
9.) kindle restarts, updates, back into setup, and NOW I have initial 5.6.1.1, NOT consumer, and verified this by successfully installing the jb with the ;installHtml in the search bar, which did blink and then restart the kindle
10.) Finish with the last hotfix step

Done. All restarted, no problems, and finally jailbroken.