I have not seen the fried circuit board, but have heard reports of an aux. water pump causing this. You might try some jumper wires direct to the batt. and aux. pump to see if it turns over like it should. Some have suggested installing an inline fuse, on the pump wiring, to prevent this.

If you have some type of electronics repair place nearby, they may take a look at it and see if it is considered repairable. (Or post some very definitive photos.)

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )