I guess USB/HID mode is what I'm currently getting, where the system recognizes the device but the kindle doesn't enable the mass storage device?
Also:
I've had the kindle charging with the power adapter for a couple of hours now. The LED changed to orange at some point. That thing sure likes to act weird. Here's hoping that leaving the kindle in usbnetworking mode overnight last night is what triggered the brick.
Thanks again for the help.