The small synthesizer the character Peyton Temple plays at the end of this episode is a Korg 770. This synthesizer is monophonic and cannot play more than one note at a time, not the chords Peyton is playing.
Toby says to Walter, "Electrocuted twice in one day, that has to be a record." Electrocution, by definition, is fatal. Walter was shocked, but not electrocuted. Since Toby is a genius, it is unlikely he would make this error.