Trouble with photon in DFU mode

Hello Everyone,

I bought this board a week back and was able to flash programs on it. Suddenly it stopped working. From the IDE it will say Flash successful but photon would still be running old code. I read on forums and docs on particle site. I am trying to use CLI to do firmware upgrade. I can login and see my device using particle list. But even though i have put my device in DFU mode (it is blinking yellow), i get this message

!!! I was unable to detect any devices in DFU mode…

Your device will blink yellow when in DFU mode.
If your device is not blinking yellow, please:

  1. Press and hold both the RESET/RST and MODE/SETUP buttons simultaneously.
  2. Release only the RESET/RST button while continuing to hold the MODE/SETUP button.
  3. Release the MODE/SETUP button once the device begins to blink yellow.
    Error writing firmware…No DFU device found

I am using Mac and have tried both USB ports. I am stuck and I dont know how should I proceed further. Any help would be appreciated.

Thanks,
Harshal

There are some tips for debugging problems with Mac serial ports and DFU mode here: