Somewhat related - but much more involved - technique: When my father worked at a major manufacturer of automated semiconductor test equipment, they were working with top of the line prototype boards - we're talking 16+ layers, more than a foot on a side. They paid extra to have the boards quick-turned to expedite development, but that meant that they sometimes got boards with defects (this was accepted per the terms of their agreement with manufacturer, particularly for the quick-turn bit). This was a decade or two ago - so those boards were big bucks. As is the norm, shorts between power and ground planes were one of the most frequent problems. If the failure could be located, they could often be painstakingly repaired (drill out short, jumper around as needed - remember, these boards cost a fortune). They would do something similar - but they'd put enough current through it to heat up the short - and then view it with a thermal IR camera to locate the short.