This movie has a great cast, with a good Christmas message and the BEST concept ever (I am a sucker for the doe-eyed time traveler who knows nothing of todays technology trope) but it's also not very well explained.
Don't think too hard on it, because there is very little background as to why the plot happens and why his quest is exactly what his quest is, but if you just wanna tune out and enjoy a silly original Christmas movie with an adorable concept extremely well executed, then this movie is for you.