What is the serial monitor actually doing?

Projects General Guidance
14 
void  serial_response()
{
   int incomingByte=0;
   if (mySerial.available()>0)
   {
      incomingByte = mySerial.read();
      Serial.print("Response: ");
      Serial.print(incomingByte, HEX);
      Serial.println("|");
   }
   else
   {
      serial_response(); 
   }
 }

If there is no data yet, make a recursive call to this function. Nope, not going to work.

You need to learn about while loops! While there is no serial data, sit on your hands and do NOTHING!