I have played around with several Netduino types (Netduino Mini, Netduino (1), Netduino Plus and Netduino 2)...
On the Netduino 2, I power it up with the button (BTN) held down (and Windows thinks the USB device is a "STM32FBOOTLOADER"). Then I'm able to download my firmware with STM's "DfuSe Demo (v3.0.3)" program. This has worked fine for three Netduino 2's that I've gotten over the past year. But I just ordered/received another one.. and the DfuSe download/upgrade seems (?) to work fine... but I can't get any response for the Netduino 2. Any thoughts on what I can try?
(The firmware I'm downloading is an extremely simple boot monitor (command interpreter) that uses USART2. And I use an ADAfruit 954 USB-to-TTL cable on Digital I/O pins 2 (RX) and 3 (TX).)
Thanks,
Tom