Check out post #11, by mtambo, in the following thread:
https://www.mobileread.com/forums/sho...d.php?t=162905. I haven't done the update myself, but these instructions seem clear and to the point. Also up-to-date!
Thank you mtambo!
That's for reflashing with the latest and greatest, but it might be a good idea, since you have a bit of knowledge, to try Ivan's suggestion first and check for any obvious damage.
Good luck! Let us know!