[shamanNS]

While connected to your computer create a "DO_FACTORY_RESTORE" file (make sure there is no extension, if you're using Windows Explorer will probably add ".txt" extension, rename the file to remove the extension) on Kindle drive and force a Kindle reboot (by holding power buttons 30+ seconds) if needed to trigger a factory reset.
Factory reset is probably needed to clean things up after firmware downgrade.

If that fixes things and you manage to boot back all the way to Kindle homescreen then do 2 more reboots and while device os starting look at that bottom section of the screen where you previously saw that "**JAILBREAK**" text if something gets written or not.

If you get to do a factory reset make sure that during the setup you skip connecting to the WiFi. And later keep Airplane mode turned on, until you get to use OTA Renamer KUAL extension no going online!
After doing all that report here in details what happened.