A really thorough flash utility would do a flash integrity test and figure out a safe place to store all the critical pieces, or at least map out all the bad blocks before flashing anything. But that would take a lot of time and folks would think their kindle died without an onscreen progress report. I suppose would could write a kernel to do that but it would need to force the internal flash processor to do things it currently does not attempt. (eMMC flash chips have their own
embedded processor, perhaps running its own
linux or similar OS).