Hi Matthew,
What??? You didn't try to make a BB-8? I guess Wall-E is a better choice, though. Loved that movie.
Start by adding additional:
else if(s == "xxxxx"){
...
}
lines for each of the appropriate buttons. In the { ... }, add the commands to stop playing the existing file, if playing, and then start the one you want.
Are you familiar with how to use the DF Player library ?
Pat.