When I was not yet two years old, my Grandpa gave me some little plastic, battery-operated, near-HO-sized train for Christmas. It came with a plastic play mat with roads, roadbed, and various other details on it and paperboard buildings, signals, gates, and so forth. He waited till Christmas morning to set it up, and the thing was DoA. *I* was too young to notice, but *he* was mighty disappointed. It went back to Sears the next day in exchange for the only Marx set left in the store. I still have that set--it's on the layout even as I type--and he learned the lesson. Every subsequent train he gave me (as long as he was able) got tested and set up running before Christmas morning.
Funnily enough, years later in '76, he took me shopping on Christmas Eve for that year's Christmas train at Sears, and they had nothing left but a pair of Santa Fe Bluebonnet Alcos. I wanted them, but he insisted that we get a whole set, so we went to Penny's and walked out with a Tyco Chattanooga Choo-Choo. It was, of course, too late to test. naturally, the next morning, the engine was DoA. Mom took me back the next day for an exchange, and IT proved to be dead, too. The third one finally worked. (Still ran as of, say, ten years ago or so; haven't had it out since.)
Still wish I had gotten that pair of Alcos 
It would have spared me a painful detour into HO. I was able to develop a few skills--the only loco kit I ever built was in HO--but, Boy! did I ever get frustrated.
Anyway, the whole story goes to reinforce the suggestion Rayin"S" made.
