I was here back in
August with the run-of-the-mill N647 "updating your software" corruption that requires replacing the SD image, and @flyboy320 kindly PM'd me the image.
Well, one night last week I finished the evening's reading on my Kobo and noticed that I couldn't put it in "Powered Off" mode, only in Sleep mode. Then the next time I woke it up, it didn't go back to the page in the book I was reading, but to a list of my downloaded books, with a different book selected.
This went on for several days until the Kobo ran out of juice (because I couldn't power it off, I guess) and had to recharge it. Two nights ago, on pressing the power button to start reading I got the dreaded "updating your eReader software" screen. For the second time in less than a year.
I had to track down the instructions all over again and then get reacquainted with the process. Fortunately, I'd kept the image that flyboy320 had sent, as well as the software to write the image to a new SD. So it was mainly a matter of reviewing the instructions before applying them.
For good measure, I ran a Linux fsck, as
described by @Altivo, on the corrupted SD card and it found quite a bit of stuff to fix.
In case the fix was good enough, I'm using the Disk Writer software to make an image of the repaired SD card: next time this happens, I'll try that one first as it already contains my books and account info, such that (hopefully) I won't have to reset the Kobo, re-enter my details, or resync it.
This all was time-consuming, but the most tedious part was having to click laboriously through each and every single page of
The Last of the Mohicans to get to where I was on Chapter 24. No joke, it took over half an hour of repeatedly pressing the right-navigation button to get back to that point. Maybe newer e-reader models let you specify a page (or at least a chapter) to go to?? On the other hand, the reason I bought this model is because it was the only one that allowed the user to put books on it via a wired connection (wife is extremely neurotic and WiFi is verboten in our home). So, as Meat Loaf sang, I may be stuck with the N647 to the end of time.