HC-06 Only receiving 255 as input

I am trying to turn an LED on and off by sending 1 or 0 (respectively) to the Arduino from Andoird Application via Bluetooth Module HC-06.
I have tried several Arduino codes and Android App Codes from the internet but the same error occurs.
I printed the data to Serial Monitor and it shows -1 (in int) or 255 (in byte) for any input.

I am very new to using the Arduino ( 2 days actually) and don’t know how to troubleshoot this. Is it a problem with the Module or the code?

Please help ASAP!

Thanks in advance.

Code:

#include<SoftwareSerial.h>

char incomingByte;  // incoming data
int  LED = 13;      // LED pin
#define Tx 6
#define Rx 5

SoftwareSerial BTSerial(Rx, Tx);

void setup() {
  Serial.begin(9600); // initialization
  pinMode(LED, OUTPUT);
  pinMode(5,INPUT);
  pinMode(6, OUTPUT);
  Serial.println("Press 1 to LED ON or 0 to LED OFF...");
  BTSerial.begin(9600);
}

void loop() {
  if (BTSerial.available() > 0) {  // if the data came
    incomingByte = BTSerial.read(); // read byte
    Serial.println(int(incomingByte));
    if(incomingByte == '0') {
       digitalWrite(LED, LOW);  // if 1, switch LED Off
       Serial.println("LED OFF. Press 1 to LED ON!");  // print message
    }
    if(incomingByte == '1') {
       digitalWrite(LED, HIGH); // if 0, switch LED on
       Serial.println("LED ON. Press 0 to LED OFF!");
    }
  }
}

Serial Monitor:

Press 1 to LED ON or 0 to LED OFF...
-1
-1
-1
-1
-1
-1
-1
-1

^ Each -1 appears on pressing the On and Off buttons on the Android app
The Android app Sends ‘1’ and ‘0’ for on and off respectively:

btnOn.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                sendData("1");
                Toast.makeText(getBaseContext(), "Turn on LED", Toast.LENGTH_SHORT).show();
            }
        })