Not getting any signal from myoware EMG muscle sensor. The signal LED (Red LED) on the sensor is always ON

This is my first time using EMG Sensor. I'm trying to read EMG signals from Myoware Muscle Sensor. When I use analogRead to read analog value, the value is almost same. There is not much change in the analog value. I get values between 676 to 680 at all time and the RED LED is always ON.

EMG Sensor I'm using: Myoware Muscle sensor from Advancer Technologies.
Arduino Board: Arduino Mega.

When Sensor is turned ON, the Signal LED (Red LED) on the emg sensor is always ON. (I don't know if it is supposed to be always ON or not ).
I have tried placing emg sensor on both forearm and biceps, but no change in the analog value. I really dont know what is wrong here.

Code:

void setup() {
  Serial.begin(9600);
}
 
void loop() {
  int sensorValue = analogRead(A5);
  
  Serial.print("Sensor Value: ");
  Serial.println(sensorValue);
  delay(1);       
}

Circuit diagram: