@JavaRocky Power switch or an option switch? Why 5V or 3.3V - do you know that either is safe? (is it still working?) What's the DC voltage on the switch? Some switches (usually buttons though) are multiplexed, meaning you can't short it to the rail. Did you connect the grounds together? Did you try grounding the switch? (It's better to measure what the switch is doing normally first before throwing random voltages into a circuit)