Are there specific symptoms exhibited by a bad PS2 5V board or are they totally unresponsive? Never had a PS1 or PS2 go south on me before. I have a GG1 equipped with 5V PS2 that quit working when I had to physically stop the engine from running away. It responds to nothing, other than if I move the power pickup switch to the pantograph position. After a few silent seconds it produces a high pitch tone, exactly like that of a smoke detector. I will probably swap the electronics with a PS3 Railking GG1 if indeed it really is dead.
Bruce