AVR Freaks

This is my send data code thanks to USB in python :

#Python imports:
import struct
import socket
import numpy as np
import time
import sys
import math
from serial import Serial

BAUD_RATE = int(115200)

################################################################################
# SendData Class #
################################################################################

class SendData:
    def __init__(self, mode, address):
        """Initialize the SendData"""
        self.is_usb = (mode == 'USB')
        self.connect(address)
        print('Initialized at address {}'.format(address))

    def __del__(self):
        try:
            self.close()
        except Exception as err:
            pass

    ############################################################################
    # Communication protocol #
    ############################################################################

    def connect(self, address):
        self.serial_address = address
        self.open_serial_connection(self.serial_address, BAUD_RATE)

    def open_serial_connection(self, port, baud_rate):
        """Open the serial connection to the 2DMOT.

        Args:
            port (str): COM port used by the arduino
            baud_rate (int): baud rate for the serial communication
        """
        try :
            self.serial = Serial(port,baud_rate)
            self.serial.timeout = 2.
            self.serial.writeTimeout = 2.
            self.serial.readline() # remove setup bytes
            # self.serial.flushInput()
            # self.serial.flushOutput()
            print('Connected to port',port)
        except IOError as e:
            print(e)

    def close(self):
        self.serial.close()

    def send_Coils(self, msg):
        if(int(msg) >= 32768):
            print("Valeur a envoyer trop grande (coil)")
        else:
            """Send a message to the 2DMOT through the USB."""
            message = int(msg) + 32768
            self.send_serial_message(str(message).encode())

    def send_Wire(self, msg):
        if(int(msg) >= 32768):
            print("Valeur a envoyer trop grande (wire)")
        else:
            """Send a message to the 2DMOT through the USB."""
            self.send_serial_message(msg.encode())

    def send_serial_message(self, msg):
        """Send a message to the arduino through va serial communication.

        Args:
            msg (bytes): message to send to the arduino
        """
        # print("Send serial message")
        try:
            if self.serial :
                # self.serial.flushInput()
                # print(msg)
                self.serial.write(msg)

                flag = self.serial.read(4)
                self.serial.flushOutput()
                self.serial.flushInput()
                print('flag: ', flag)
                if flag == b'':
                    print('The 2DMOT encountered some issue while treating '
                        ' flag ', msg[0])

        except Exception as err:
            print(err)

###########################################
# Constants #
###########################################

MODE = 'USB'
BOX_SERIAL_ADDRESS = 'COM7'

################################################################################
# Initialize #
################################################################################

CTRL_SendData = CTRL_SendData.SendData(MODE, BOX_SERIAL_ADDRESS)

################################################################################
# Send values #
################################################################################

if __name__ == '__main__':

    CTRL_SendData.send_Coils('400');
    CTRL_SendData.send_Wire('450');

With Wireshark, I can see that my data is well send :

But the program in my programming card reset when I compile the python code... And I know that the program reset because this program have a display which display randoms values and when I compile the python code, the display reset and the randoms values too (the 1st random value is 0 so I can see the reset).