Long story short, I ran the battery down while attempting to flash, and got to the point where battery was low. Pulled the cover off, charged through the terminals on the back and battery is now "OK." Now, the phone won't enter fastboot when plugged into a computer or unplugged. If I plug into the wall charger, it immediately tries to boot (and fails, sending to fastboot) and will let me hold the three buttons to enter fastboot on my own. If I unplug, everything goes black. Once unplugged, I can't do anything. I'm not even getting the screen flash when holding the volume down+power for a while. Same thing with the computer. I get the white LED, but no buttons have any effect.