How do I diagnose a short and replace the correct parts?

I have an original 7D. When I trigger the flash to pop up, something shorts out. The camera power cuts off immediately, and the (aftermarket) battery discharges about 80% of what charge it had.

A 2012 post regarding a different issue referenced the possibility of screws getting loose inside and shorting the flash PCB on the bottom.

I have direction on how to get to the board and replace it, but is there some way to diagnose the short to determine ahead of time whether simply replacing the board and getting the screw back into place will fix the problem?