@kobrick: Does a hard-reboot via paperclip (I'm partial to toothpicks, but both work) (the button/hole is on the right of the USB port, if memory serves) help?
EDIT: Checked, yep, on the right, first tiny hole, not the second larger one. The button has a strong tactile and audio feedback, don't be afraid to get in there

. A simple click should be enough to trigger a hard-reboot, no need to long-press it. It may take a while for you to get any feedback though, be it from the screen of the power LED.
That *may* trash your Nickel settings and/or DB, but then those are probably trashed already, so... It won't format the device, though, so if you have a backup of those (i.e.; from Calibre), that's pretty much a non-issue besides a bit of time lost

.