Firmware update issue "upload failed dfu device disconnected"

I'm having difficulty updating the firmware on my puckjs. Once in DFUTarg mode;

• if i try to upload the firmware in NRF Toolbox i get the message "upload failed dfu device disconnected"
  
• if i try try to do it using NRF Connect, when I select the device I get a connecting spinner and never get the DFU icon in the menubar shown here https://www.youtube.com/watch?v=N3CJbl29­vy0
  
  
  
  
  

Any ideas?