Well i made some pictures that may help, if you want two buttons to make one go up and one go down, do this:
Make a variable, "Above Ground" to represent if its above ground. Now make an If/Else statement like shown and and make it == false, so if its not above ground, it will come up. And the events are shown up top.
Left are just the methods used, and this picture shows the vice versa of the image above this to do the opposite.
Now, if you want it to be so that it just does it once and only once, make it like shown above, so if its pressed, it moves the cube down and only does it once, since the variable would be changed, pretty much doing the "Cube Down" method in the images above this, but just only doing that not including the other.
Hope this helps.