If the update tool keeps running for longer that 15 minutes in step 5, you can terminate the application via the Task Manager on Windows (Control+Alt+Delete) or Force Quit Applications on Mac (Option+Command+Escape).
The first thing you could do, is simply try again, maybe using a different USB port to connect your ZERO. In between attempts, you need to turn off the ZERO by pressing the power button for 5-10 seconds, and activate update mode again.
If after a few attempts it still doesn't work,please contact support@ngrave.io.