I've read through the tread you're pointing at.

There is an answer for what was wrong during formatting the SD card back then.
That was it! Originally, I had formatted a brand new card, and named it, but the directory structure had not been created.
This time, I took an existing card with enough room to hold the file, and just copied it to the root. It worked the first time..."

Does the directory usually created when format SD card using KN2600 show up?
If not, the SD card may not be formatted correctly.
Also I notice the filename is written using big letters.
We never know, maybe rename the file like in in Alecs reply kn24prg.dat just to see if it makes any difference?

It looks like the filename itself is correct, and the file is most likely the file needed as long as it is not damaged or not copied properly.

Quote regarding size of the SD card:
"the official instructions say use a card bigger than 8MB formatted on the keyboard to hold the file."

Also it say something in the tread about renamed the card, but I have no idea about what name or if it is nessesary at all.
Maybe as simple as name the card UPDATE ?

in the update manual it say the update fix problems reading / loading of older instruments files, nothing about technichord,
but CraigS mention the problem without any feedback if that was fixed by the update at all.
Cheers 🥂
"Success is not counted by how high you have climbed
but by how many you brought with you." (Wil Rose)