After much learning tonight, I finally got my old unit updated to the following.

DeviceName=TomTom ONE
DeviceVersionHW=ONE (v7)
BootLoaderVersion=55001
ApplicationVersionVersionNumber=8010
ApplicationVersion=9369
CurrentMap=USA_and_Canada
CurrentMapVersion=870.3417

Everything works, including the voices and car icons I had in there previously. What a great site! :-)