I would not use the continuity tester at all since the Voltage of the continuity tester on some multimeters can provide up to 9V that’s quite a lot for chips that are designed to handle 3.3V or below.
Try measuring the Voltage between the 3 pins of the switches while the Phone is switched on an then see if something changes between the Pins depending on the position of the switch.
But that’s just my option.