djmauro:
@McNibbler I had exactly the same experience - brand new genuine Arduino Nano. However, until I identified the board as Arduino/Genuine Uno I could not upload any sketch. This is indeed totally messed up. Anyone know what is going on?(One more observation: the 'L' led blinked with a one second on and off cycle.)
Update the AVR board package using board manager to 1.6.21 (1.6.22 and 1.6.23 have a new bug) - then the new bootloader option will appear for the nano.