I purchased a Netduino 3 Wifi last week on Amazon and it has been working very well. I ordered two more Netduino 3's and received them today. They are both working fine too with the 126.96.36.199 firmware. However, when I try to update the two new boards firmware to 188.8.131.52 using that version's NetduinoUpdate.exe app, I get a "Stem device in DFU mode". I select options and set the product to Netduino 3 Wifi - see attached pic. When I try closing the Device Options window, nothing happens. I eventually have to force the app to close, therefore not being able to update the firmware. I did not have this problem with the first Netduino 3 Wifi I purchased last week, the update app properly identified it as a Netduino 3 Wifi and I was able to update the firmware.
Thanks for the help and I'm very much looking forward to using this new board.