I had been running a Seeeduino Mega on a +12V source for some time with no issues. Then I managed to ground the 5V pin. The MCU got really hot, even melted a rubber band that was near. Now whenever I plug the board to a 12V supply it immediatelly heats up to >75C! Purrs like a kitten when running from USB though.
The theory is that the 5V regulator got damaged when the short occured, and now it's putting out a higher voltage. I'll measure the output when I get home, but for now, is this a known failure mode? Are there any periferal (around the reg) discretes that often fail during an overload like this or is it a regulator failure?