It would appear that the controller is "locked" in some way to data firmware.
(I have NOT checked if data firmware fits a graphics controller - usually you would want to upgrade from Data to Graphics)
There has been talk of "unlocked" controllers but I have never seen one, nor ever found any details about them.
It is possible this is a myth started by Marwuee owners
SO to swop a data PJ towards a Graphics then a "Graphics" controller and firmware is needed
This is only PART of a data to Graphics upgrade
Eproms from Greg are here