In that case, you might need to find the board and install it yourself. If you're comfortable doing a little electrical work, that is.

Disconnect it from the power source, open the box and examine the panel circuit board. You will probably find a part number printed onto the circuit board its-self. Then you can search the internet or call them and ask about parts. Replacing a circuit board is usually very simple, just take pictures before you disconnect wires, and put the replacement in where the original was.