Hold function for Pocket Piano MIDI

Hi hi. My Pocket Piano MIDI Silver with 6 modes doesn’t have the ”Hold” function, which I really really wish it had. (also, using an external MIDI keyboard with Sustain Pedal CC64 doesn’t work)…
Is there a way to get the firmware update necessary for this upgrade? I’m totally ok with any kind of DIY.

I also have one without the hold function or 7th mode - totally would love if it was possible to upgrade it…

Hi & Thanks for getting a Pocket Piano! Unfortunately we are no longer offering the service to upgrade Pocket Pianos built prior to summer 2014 with the ‘hold’ function and seventh mode.