The switch is momentary contact and sends a signal to a microcontroller to turn the power on and off.
Shorting out the switch so you don't have to press it, presumably to turn it on/off by an external switch may or may not work, depending on the microcontroller code. You can test if shorting out the switch will work. Unplug the unit from the wall. While pressing the switch, plug it back in. Does the unit start and operate OK? Continue pressing the switch. Is the unit operating properly, without any glitches of any kind? If so, shorting the switch should work.
If any glitches occur, like shutting off while you're holding the switch or failing to control operation properly, you're out of luck.