I received the wrong buttons in the mail and want to purpose one of them as a reset button for my device. It is normally ON and I'm not sure how to wire it to send a low to the arduino when pressed.
I used a pull-down resistor connected to ground on one end and connected to one terminal of the button and the reset pin on the other end. The other end of the button is connected to +5V. It's not working properly at all.
Is this a 2-terminal button, and it is normally closed?
I wouldn't connect that, it will keep software reset from working when you want to do an IDE generated sketch upload.
Yes and yes. I have it undone while I update the software but I am building a permanent enclosure for it so I need an external pushbutton for reset.
Won't work. Reset would normally be pulled up by a resistor, then the push button connects it to GND to perform the reset. So to reset your pull-down resistor should be small enough to pull the voltage down enough to cause a reset. Will give you lots of current leakage as you'll need a really small resistor there, probably in the tune of 100 Ohm or so.
You could use a PNP transistor and three resistors to cobble up an inverting switch? Here's a link to a simulation of the circuit:
edit
probably use higher value resistors to reduce current consumption. Shouldn't change the functionality of the circuit... it simulates just fine with 1M resistors.