[shamanNS]

If it doesn't mount on you computer even for a second then there is no change to try do add DO_FACTORY_RESTORE file to try and trigger factory reset and hope that fixes the issues.

It's curios that it manages to boot up to that point of starting jailbreak bridge Upstart process (that prints that *** JAILBREAK *** text, while it tried to restore various parts of jailbreak survivals setup).

That wasn't the case with my PW5 even though it was jailbreak-ed, maybe because mine had older version of jailbreak hotfix installed (since my PW5 had firmware 5.14.1.1)?
Mine doesn't even get to displaying that loading progress bar thing or print any text from jailbreak bridge, it stays on image of Amazon tree thing and reboots after 15-20s.
Of those XY seconds between two reboots my PC detects the Kindle as a removable drive with size 0 and no partitions / no file system detected for something like 3-5 seconds.