It took a few tries but it seems to be working. I am on a Mac and had to first plug in the USB cable, select PC Suite Mode, and then start up the map loader. It has been running for about 1.75 hours and is about 45% through step 1, deleting the old map files. It says it can take a long time and it means it. I will post more when I have some results, one way or the other.