I would question whether a driver went bad or if it is part of the board that wigged out on you. Either way if the board died then I would bet parts don't exist and the drivers most likely don't have the balls to drive any COB that's worth a darn to make it worth your time and effort to covert it over with the hardware you have.
Now to just be able to use the housing, fan and fan driver you could stick a Cree cxb3590, Vero29 or a Citizen CLU048-1212 into it with a Meanwell LPC-60-1400 driver and have a 50'ish watt light.Granted I don't know if you would have room inside of the case for the LPC.