Unfortunately if neither SD method worked it seems likely the flash is indeed damaged, all the evidence from your previous very capable attempts with Cure fw and now its failure to complete the commands with patched boot.rgn confirms that for me. I'm unsurprised that the usual method with Ldr.bin didn't work as it very often doesn't with bricked devices. However, kunix's patched boot.bin as RGN doesn't rely on firmware initiation at all so it should have allowed the regions to be dumped, provided the flash chip is healthy to my lay understanding. Not 'rebooting' is itself unremarkable [of course it wouldn't 'boot' as such but would instead return to that bootloop state of constant restart attempts had it got to the final command]. The concerning point is that it was stuck on 'Loader' trying to initiate the initial command to dump rgn41 with nothing happening as evidenced by update.log and last_id.bin absence. 7xx series can read/write both FAT16 and FAT32 formatted SD cards.

Sorry, i'm out of ideas for a soft solution. For a physically damaged flash chip the only solution is its replacement. That's an arduous process requiring unsoldering the chip and resoldering using reballing technique also the new chip requires reprogramming to suit the unit all of which you'd already be aware as i suspect you're not inexperienced in electronics and software and/or IT generally. That is not at all a reasonable solution for fixing such an old device and i would now break it down for parts. Perhaps one of our software experts has another suggestion for a non-invasive fix and if so they'll post. Although i think it's quite unlikely there may be still hope for some type of 'cure'.