Hey dutchmonkey,
I had a minor glitch while flashing my Arduino as well. Edward has a help.doc that I believe is linked from one of his ERC instruction videos on his YOUTUBE channel. If not you can PM him on FACEBOOK and he may help you direct. He helped me. My issue was fixed in a minute.
My problem was simple--I did not realize after I had flashed the Arduino 3X it had actually taken the first time. When I was checking it in the GRBL program I simply had my "BAUD RATE" at the default--If you set it to the max setting - ~ 11500 it works. It was a simple setting issue. Not sure if this is the problem you are seeing, because I thought my Arduino was not flashing either!!
Hope this may help. If not, PM Edward Just remember there is a time difference.