the firmware file should be downloaded to an sd card.

hold down piano, strings and guitar and switch on to confirm existing level.

the official instructions say use a card bigger than 8MB formatted on the keyboard to hold the file.

run the exe and write the kn24prg.dat file to the root of the sd card in a card reader.

transfer to keyboard, hold down first 4 panel memories and switch on.

perform the check procedure, wait until finished.

switch off, wait a few seconds, repeat performing the update procedure if the check was ok, wait until finished.

switch off, wait a few seconds, check new level.