If you ever unplug the unit from the car's outlet and let the internal battery run completely dead you have to press a reset button to get it back on. More than likely the previous 2 you owned did that and were fine.
I have had the same unit in my vehicles for years and found out about that the hard way. I thought mine had bought the farm when it stopped working. I was coming back home to GA from a hunt in CO. My BIL unplugged mine to punch in something and never turned it off or plugged it back in. We didn't need it for several hours and it wouldn't work when we did plug it in. Got on the wrong road coming through St. Louis and cost us about an hour. My BIL figured it out and it has worked fine since. That was 2010.
Garmin has been good to me. I broke the screen on my handheld, a $400+ device and they sold me a new one to replace it for $100.
