I need help! I have a long story, but it is about a Korg PA80 and a Kohler Baby Grand

I have a Kohler Digital Baby Grand which is a Korg PA80 guts. The main board, the KIP 2025, faild. So I got one out of a PA80, but the PA80 is 61 keys and the Kohler piano is 88 Keys, so the result is not right. Do i need firmware to change the main board? Help!