So I need a motor or actuator of some kind to push and hold a button, then release. But my concern is if there is a loss of power or some kind of problem with the arduino, that button needs to be released automatically, it cannot be stuck on in any situation.
I will include a micro-switch so the arduino will know if there's a problem eg. the button was not depressed correctly.
My thoughts are on a servo motor like on an RC car, but the servo motor I got with my arduino starter kit doesn't seem to be possible for a spring to pull it back. Perhaps there's other kinds of servo motors.
On ebay there are "linear electromagnet solenoid push/pull" but without having one in my hand I'm not sure if that will do the job.