Update: Fixed.
I was able to use ArduinoISP to reload the bootloader using an old MEGA as a programmer. This revived both boards and I was able to reload Blink - they feel new again.
So if anyone has an issue with the Leonardo not showing the serial port after loading a sketch, download ArduinoISP and use as directed. If the only other board, this may help (I didn't have to do that since I had other boards around to use as a programmer, just a FYI).