Python Kivy App connected via Bluetooth with Arduino UNO

Hi,

I encountered and issue with my kivy program. I want to turn on and off a LED using 2 kivy buttons. The program is running, but doing nothing, no error nothing. The connection scheme with Arduino is correct, I tried with a code without kivy and it worked. I this the issue is by the serial communication.
Do someone please has a clue, where the issue is?

Thanks,
Andra

I paste the code here kivy:
import serial
import kivy
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.label import Label

class ChatApp(App):

def build(self):
    #reconnaissance de la carte Arduino:
    self.Arduino = serial.Serial("COM6", 9600, timeout = 1) 
    
    
    #On cree une disposition pour l'affichage:
    Layout=BoxLayout(orientation='vertical',spacing=40,padding=(200,20))
    
    self.Bouton5=Button(text='5')
    self.Bouton5.bind(on_press=self.send)
    #On ajoute le bouton dans l'affichage:
    Layout.add_widget(self.Bouton5)
    self.Bouton6=Button(text='0')
    self.Bouton6.bind(on_press=self.send)
    #On ajoute le bouton dans l'affichage:
    Layout.add_widget(self.Bouton6)

    #On renvoie l'affichage:
    return Layout

def send(self,instance):
    self.Arduino.write(b'instance.text')

if name == 'main':
ChatApp().run()

Arduino Code:
#include <SoftwareSerial.h>
SoftwareSerial HC06(10, 11); //HC06-TX Pin 10, HC06-RX to Arduino Pin 11

int LED = 12; //Use whatever pins you want

void setup() {
HC06.begin(9600); //Baudrate 9600 , Choose your own baudrate
pinMode(LED, OUTPUT);

}

void loop() {

if(HC06.available() > 0) //When HC06 receive something
{
char receive = HC06.read(); //Read from Serial Communication
if(receive == '5') //If received data is 1, turn on the LED and send back the sensor data
{
digitalWrite(12, HIGH);

}
else digitalWrite(12, LOW);//If received other data, turn off LED

}

}

I'm not sure the pySerial library has Bluetooth functionality. I would use pyBluez as it provides for bluetooth communication on desktop (Doesn't work for mobile). If you want to make it an android app, use pyJnius to access the bluetooth api. If you do use pyBluez, beware that it may not be easy to compile into an exe because the current version has some bugs. If you are just wanting to run it from your computer/terminal though, pyBluez works fine. Here is a link to an app I made to control a Bluetooth RC car (ESP32) with Pybluez. It shows the Bluetooth code pretty well.
Here is another version of the same app but with Jnius.

When installing PyBluez, I strongly suggest using the PyBluez version and buildtools config found in this folder, installing from source. I have tested it and it works without issues.

Hopefully this helps!