What buttons do not work? If you're talking about the last buttons when you win or lose, those are meant to not work (because I didn't have time to think about how to make it work). Instead, you have to press the red and blue buttons on the top left corner of the screen.
The dice rolls are show on the top middle of the screen (Roll Result...)
The modifiers work like this: Whenever you roll a stat, for example INT, you will roll a d20 (a dice with 20 faces and numbered from 1 to 20), then add the modifier. That will give you the final result that I write on the roll result. I didn't have the time to write like 14 + 2 = 16 or sth, that would probably make the rolls more clear.