Power supply heat problem

I’ve got this breadboar power supply 3.3/5V:
and got it connected on a breadboard to a standart Particle Photon board with headers:

It all worked fine and I put it all into a solder prototype board. The project was to control three solenoids. I’ve followed exactly the tutorial here with transistors, reverse diodes and gate resistors. Something went wrong and I don’t know what I’ve damaged.

So I took everything out of the solder board and put it back on the broadboard to diagnose. Only the photon and the power supply.

Now, when I connect the Photon to power it starts ok but after about 10 seconds it turns off (the blue D7 LED shimmers weakly). At the same time, the voltage controllers on the power supply get burning hot. The voltage drops during this time. Without the photon the voltage stays at 3.3/5V with no heat. I’ve put a 1.5 ohm resistor in series and measured the voltage to get an indication of current and it was about 250mA, which seems a bit high for the photon but the power supply should handle it. Visually, the only thing I can see is a silver-ish dot on the large black element right behind the USB port.
Any idea how I can find out whether the photon and/or power supply are dead?