Garmin powering off
I had the same problem with my 305, which I had working for a good couple of years without problems prior to this, and it does worsen over time. I would not recommend trying to open up and fix the unit, if at all avoidable, since this may void your warranty. If you still have it under warranty, as mine was when it occurred, you can contact Garmin directly for a repair order number. Their customer service was excellent for me. I sent out the defective unit to somewhere in Kansas I think and had a new one in under a week. It has been flawless again since I installed it. Good wishes with this.