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When dealing with an update for your Garmin device, it is best to simply download, install, and use Garmin Express.
and (if you have a Windows PC) click on the big blue Download button at center bottom of the page.
(If you have an Apple, click on the nearby Download for Mac link.)
And download Garmin Express' installer to your computer, save it, then double-click upon it to install Garmin Express.
Then start the program, Garmin Express. Then connect your Garmin device, with a USB cable.
Then use Garmin Express to update your device.
As for registering: if that doesn't do it, then it's probably superfluous... your device is well past warranty, so for warranty purposes, registration would be of no use. But I suspect registering it isn't necessary - the Garmin Express procedure should take care of everything you need. (If it doesn't, let me know!)
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