Step 1 was probably a mistake!
You might have lost your JB for good. Usually, you shouldn’t let Kindle update/factory reset twice in a row on a new firmware (that doesn’t support JB).
However, chance are still there, try emergency.zip instructions in the end of this post:
https://www.mobileread.com/forums/sh...&postcount=484
Go to Airplane ASAP.
Delete any new remnants of update.bin.partial files on Kindle storage.
Put the four files on Kindle and restart.
If they disappear after Kindle boots back, you are good - install hotfix from NiLuJe via mrpi.