For mine, there has been separate firmware updates for the CPU and the GPS receiver. I had to make an account with Garmin and register my device; hopefully you'll be able to do that, or not need to. Either way, you will need to download the appropriate "Garmin Web Updater" and that will sync your device with your computer, with Garmin Update options.

Next time you're going to the woods, try to have the unit on beforehand and a good signal before you get under the canopy - see what happens.