Given how the actual transformer power is conveyed to the outputs, it's pretty hard for me to imagine that enough current is flowing through the PCB to actually heat up the transformer if there is no load on the output! When you trace the actual transformer power through the circuit, I'm not seeing how you get a short that would heat anything up, the 68 ohm resistor at R2 seems to preclude any shorting. Now, I can imagine a possibility of a major meltdown on the board maybe, but that will be obvious by casual inspection, but I'm rating that possibility as very unlikely.
