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It sounds as if it has failed to initialize, or is sticking during startup, so first try removing any accessory connection, or memory card, from it while it is turned Off, then try starting it up again.
I think that since those measures you have tried already have failed, you should try updating the (possibly corrupted) software on the Garmin device with Garmin Express. 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. Then use Garmin Express to update your device.