make sure that you input pin is pulled up. You can do this with pinMode(sensorPin, INPUT_PULLUP);
Also note that A5 is indicating an analog channel. A5 when using it in any of the digital API's translates to pin 5 which is P1.3.
So rather than using int sensorPin = A5; I suggest that you use uint16_t sensorPin = P1_3.
Since count is being increased in the interrupt routine, you will need to make it a volatile. Simply said, volatile means that the value can change at any time. so that would be volatile uint8_t count1;
Below is a small example that will toggle the red LED when the button is pushed.
int pin = RED_LED;
volatile int state = LOW;
attachInterrupt(PUSH2, blink, CHANGE);
state = !state;