I bet you just didn't give it enough time and driving around not giving it constant reception isn't making things easier for the unit either. You've had it locked up to long for it to remember the useful stuff (almanac data) it needs to aquire reception fast.
To speed things up you should start by pushing the Menu button when on the satellite page. Choose "New location" from the menu, then choose "Use map" and tell the unit where you are. Next you put it where has as much clear view of the sky as possible and let it receive satellite data for a while. Normally it would get fix within one minute but if reception is in any way obstructed (being next to a building, under trees...) it can be significantly worse so just leave it for 15-30 minutes.
If that doesn't help try Geckos master reset but make sure that you back up any important data from the GPS to your computer first if necessary. Then try the things I described above once more.
If that doesn't succed it's time to call Garmin service but I'm pretty sure you will bring it back to life yourself.