Here's an old You-Tube video that Lance (mx270a) put on for upgrading software = it helped me this Spring:
https://www.youtube.com/watch?v=er6gZC3bxyo
Mine was an "Ag Leader" branded 500 unit:
https://talk.newagtalk.com/forums/thread-view.asp?tid=853403&posts=2#M7494544