Thanks for all the help. I think I found it!
Putting this edit on top of the post so that people read it first.
I got the device recognized as a Kindle, and am now able to flash system images onto it. Anyone know where I can get a Kindle Fire 2 system image?
The screen suddenly lit up and I have an icon that says "Fastboot kindle fire".
I have a new device now:
fastboot devices still gives me a blank line, and I still get the "waiting for device" message.
Also, my device did not "install correctly." I tried to install it looking for driver software online, but that didn't work.
And I am running fastboot with elevated privileges.
I succeeded in bricking my Kindle Fire 2 last month while trying to install an Android operating system (yes, I know, I should have been more careful).
Today the fastboot cable arrived and I connected the Kindle Fire 2 to my computer. The screen is still black, but when you press the power button, a picture of a low battery with a charging sign pops up momentarily.
I tried to flash my device with fastboot (in the android tools), but I get the text:
< waiting for device >
When I run
fastboot devices, I get a blank line (no devices).
I'm running Windows 7, and when I looked at the device management, I couldn't find my Kindle or anything like it (might just be me, though). I unplugged the Kindle momentarily and saw no change in the device list (which usually refreshes when a device is added or removed).
Any ideas on what's going wrong and what I can do to get my device recognized by fastboot?