I’m surprised this wasn’t mentioned in the original write-up, this is called the 4-wire resistance measurement and is a standard and very effective in locating shorts on power planes, even multiple shorts, on a board—you look for the relative minimum voltage in an area. I never run more than .5 to 1 volt since the current sometimes burns out the short if it’s a whisker, then you’re left with that voltage running around the board. One thing dennis didn’t mention is be sure this applied voltage is the correct polarity so that if the short suddenly disappears, you dont have negative power, although this is rarely an issue at .5V. This and never, ever power up a new board without a current limited supply.
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