My Garmin 1000 had a tendency to shut down mid ride. I took it to bits and found some corrosion near one of the screw holes, bottom right corner when viewed from behind. Careful examination revealed a small crack in the post the screw went into, ice damage, or maybe from a drop? I carefully removed the corrosion, put waterproof grease into all the post holes, put it back together, more grease in screw holes, and then put electrical tape over all the screw holes. Touch wood it's not shut down since.
Since then the plastic/rubber over the power switch has failed and is also taped over.
I do have an issue with charging over USB from computers, from time to time it gets it's knickers in a twist and won't start recording a ride, indicated by distance not going up. Hitting stop then says I've done a ridiculous number, 26834 or something like that, and the ride can't be deleted or saved. Have to do a hard reset. Annoying if I don't notice at the start of a ride, irritating if I notice at the start as it means waiting for the reboot and GPS acquire.
Given the battery is on its last legs, I get about 7 hours out of it which is close to some rides I do, I suspect I'm going to replace with a Wahoo next time round, it is painfully unreliable. Although I was riding with somebody the other day and their Wahoo stopped recording mid ride....