Have you checked if your Oasis after factory reset still checks for and runs "emergency.sh" script? To determine if that can be used to restore/undo rename for ota binaries so that you can then reinstall the hotfix using "Update your Kindle" option instead of having to redo everything from scratch.
https://www.mobileread.com/forums/sh...sh#post4563018
https://www.mobileread.com/forums/sh...sh#post4595159
If emergency.sh script doesn't run your plan B for restoring OTA binaries would be to manually download and reinstall the SAME (still jailbreakable, hopefully) firmware version it's already using and after that redoing the same jailbreak method you used previously and are already familiar with.
https://kindlemodding.org/firmware-a...g-updates.html
Obviously change the numbers at the end of the download link to choose the version you want.