I went to the map menu and the new maps were not displayed. All I had were the two that came with the car:
CN North America NT 2014.20 3d and CN North America NT 2014.20

For some reason the new maps don't see to be detected. I also tried following the instructions in the Piston Heads forum Free OpenStreetMap maps on Garmin Sat Navs - Page 1 - Aston Martin - PistonHeads UK . I created a Garmin map file with for the western US and copied the files onto a 64 GB SD card (the card was way bigger than I needed). That file also wasn't detected. Very strange.

 

Strange. Almost sounds as if the SD card isn't seating properly.

 

That did occur to me. I've tried three different SD cards and they all click into place. I hope that it isn't a bad box that just can't read SD cards. My hope was that there was some magic that I could invoke in a menu somewhere to get the nav system to look for files on the card. Hopefully I'm not the only person that has had this problem and someone else has already solved it.