Without the batteries in them if you look at the border of the screen, Across the top and bottom is where the icons are, but down the sides on a v1 the design is horizontal lines going down and the background is a heart, Down the sides on a v2 the design is 3 circles and the background is checkers.
I could very well be wrong but thats what I gathered from many different pictures and searching for about an hour lol.
I would say the v2 would appear to be more updated looking then the v1 (example : brightly colored, less scratches)
Packaging would say v1 or v2 on it, if its in the package.
If your getting it from a store, Just ask an employee to be sure.
If your getting it from a friend, Ask them to see if they know.
Good luck =)