Interesting approach. I expect a thermal camera would locate the fault very quickly.
Just the other day I was using a large electrolytic cap to blow open shorts on a two layer board. Plenty of microscopic shorts to the ground plane, The 0.2mm gap is a bit too small. The cap method is very effective for small shorts that a 3A PSU cannot blow open.
From now on I have opted for bare board testing at the PC board manufacturer.
Dick