Dog Tags (2016)

A grandfather who knows he's dying uses a time machine to visit the grandson he never knew. Knowing he'll die shortly, the grandfather desperately wants to enlist the help of the grandson in a last-ditch attempt to heal a years-long emotional rift with the boy's father over a set of dog tags. Things don't go as planned however, when the grandson's klutzy friend triggers the time machine and sends himself back to the grandfather's workshop.