[Xenophon]

My Mom's Kobo Clara HD won't boot (or reboot). Sequence of events:

1. I had it connected to my Mac so I could use Calibre to load more book for her. It unmounted itself all on it's own, yielding a "disk not unmounted properly" warning from the Mac OS.
2. Screen flashed black-white-black-white.
3. No response to short presses on the power button.
4. Attempted a normal reset: Hold the power button until reboot begins. Saw the three dots that slowly refresh while the system boots.
5. Got to the end of that sequence, where you normally get the UI next. Instead, got a flash-to-white-screen.
6. Now, If I hold the power button for 20-30 seconds, I get the black-white-black-white flash, but nothing else. No reboot of any kind.

I can't update firmware, because I can't get the a point where it will mount as a USB drive. I can't seem to get back to the UI, no matter what I do.

Any suggestions for reviving the apparently-dead would be extremely welcome.