Another user experienced the same problem in
#34.
If you have soldering skills, you can try this method to unbrick your Paperwhite:
https://gist.github.com/ramast/58633...2ecc96965d48ed
I’m not aware of any other methods at the moment.
I added a warning about this issue in the description under the "Block Device Logging" section several months ago. Sorry for not placing this warning in a more prominent location.