When Home Guard is not armed, pressing the arm button arms the system. The user is prompted for a password for Arm and Disarm

HomeGuardFixtures.ActionFixture
start	HomeGuardFixtures.FrontPanel
check	display	READY
check	arm led	off
press	arm button
check	display	ENTER PIN
enter	digits	3141
press	enter button
check	arm led	on
check	display	ARMED

Pressing it again disarms the system.

HomeGuardFixtures.ActionFixture
start	HomeGuardFixtures.FrontPanel
press	arm button
check	display	ENTER PIN
enter	digits	3141
press	enter button
check	arm led	off
check	display	READY