Now that You've loaded the cure can you see the files and folders inside the nuvi ?
If you can delete /.system gupdate.gcd and go back to garmincure3.
Do the same as you did before except this time do not "make cure" use "make firmware."
Then reflash the Nuvi again with the firmware. It's worth a try.
Maybe you are still running the cure firmware now.
And what is this "cat" you speak of, the screen should display the Garmin logo.