As you can see in my other thread I am expanding my RMax with an autoshutdown and thermal fuses. Now a second problem has risen. When is switch on power the board does not light up and no fans are blowing (I have 2 fans directly on the 12V circuit) I hear a ticking sound, looks like my 12V stepdown is clipping. I am measuring 20V to the 12 V stepdown, but 0V on the 12V side of the stepdown. When I disconnect the board from the 12V line, the fans blow normally, and I get 12.5V out of the stepdown. So something must have happened to the board. The only thing I did was soldering three pins on the 5V, PS_ON and GND. I am measuring max resistancebetween all of those pins, so there is no short. Also I am getting max resistance on the Vin connector. When I connect a USB charger the board boots normally and I can get into the WebGUI (I have no paneldue).
What could be wrong and how do I go about testing that?