Factory reset First Alert zwave smoke and carbon monoxide alarm?

Can anyone tell me how to factory reset a First Alert Smoke and Carbon Monoxide Alarm? Instructions tell me to push the button at the top of the detector. I can't find any button. I did the open battery compartment, remove and replace batteries, hold test button while pushing in tray, etc. I can remove these devices from my system, but every time I try to add them back they join the wrong network.