Garmin GPS loses power

I have a handheld Garmin GPSmap 76 unit that keeps shutting off after about 1 minute despite installing new batteries(twice). This unit has been flawless since Day 1, and with the numerous waypoints/markers already in it's memory, I'm afraid that they will be lost should the unit need to be "sent in". Any ideas as to what would make the unit keep shutting off? All I can do now is pop the cover and pull out/then replace the batteries, put the cover back on and press start/on and it starts up normally then goes blank after a minute(a line shows from top to bottom but pushing any buttons doesn't do anything else) I'll probably have to call Garmin on Tues. but WC has a LOT of intelligent anglers so I thought I'd throw this one out to them, while waiting for Garmin. Thanks in advance !!

I have the exact same unit that is around 4-5 yrs old.After much use it was doing the same thing. I got on the garmin web site for info and price(90.00 us)and sent it in.Had a brand new unit with all my old waypoints delivered in 3 days.This was 3-4 months ago.

[benlilu]

I called Garmin and was told to reset it by hold power on switch for 15~20 seconds. And it is turn on successfully. Also was told to use a USB cable to connect to a computer to get software update. Now everything works perfectly without any charges.

[yarcraft91]

I have a GPSmap 76 that's been flawless for so long I forget when I bought it. Do you have the cigarette lighter power cable for yours? It may run longer off an alternate power source.