Troubleshooting is best left to the techs on the ground. From my general background, it appears that the two separate incidents you mention are interrelated.
First thing to look for is to see which bus powers each PFD, and then, if there is a link between the Buses, i.e. some sort of Transfer Bus and I would start looking there.
Having said that, I just want to reaffirm that I am not familiar with the type you mention but this is just general info.