Keys, as in the white/black keys? Or keys as in buttons?
If the notes, it's really easy.
^ My Indigo.
^ Turned over, all highlighted screws need to be removed.
^ Turned over again. The keybed now slips out!
^ The keybed is still attached via a ribbon cable, shown highlighted, so this needs to be disconnected.
^ Indigo sans keybed.
Of course the Indigo will be different to yours, but hopefully not too much.