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To check if the expansion board is still ok, you can open it up, and then use a multimeter’s diode test function to check the gate to ground forward drop voltage on each of the triac. Specifically, open the triac’s datasheet:
page 2 figure 5 shows the pin names of the triac. Put the multimeter’s positive (red) probe to pin 3, and negative (black) probe to pin 1. The forward drop voltage should be somewhere between 0.6 to 0.7 volt. If it’s very low or there is no forward drop voltage that means the triac is dead.