main.py file with MQTT protocol that can connect to AWS Iot core is not working

Question

I have been working on Pi Pico w board that connects to AWS Iot core using MQTT protocol and my code is working fine when run on IDLE. But the problem is when i save my file as main.py and trying to run it just connecting to internet source . It is unable to establish a MQTT connection .I have also checked the internet connection it is fine and I also placed all the files like private key , cerficate and CA1 file in pi pico w board itself. But I couldn't understand wha'ts the problem is!! This is my code: In this code i just want to place a randomly generated number in the AWS Iot Core.If it works i will continue with the actual implementation of my project.

import wifimgr #This is another python file that takes care of internet connection
import machine
import gc
import network
import ssl
import time
import ubinascii
from machine import Pin, time_pulse_us
import utime as time_t
from simple import MQTTClient
#import config
from random import random

try:
    import usocket as socket
except:
    import socket

led = machine.Pin('LED', machine.Pin.OUT)
wlan = wifimgr.get_connection()

if wlan is None:
    print("Could not initialize the network connection.")
    while True:
        pass

led.on()
def blink_led():
    led.off()
    time.sleep(0.2)
    led.on()
    time.sleep(0.2)


print("Raspberry Pi Pico W OK")

MQTT_CLIENT_ID = ubinascii.hexlify(machine.unique_id())

#PLEASE NOTE THAT ALL FOLLOWING FILES ARE CORRECTLY NAMED IN MY CODE , I HAVE JUST MODIFIED THEM DUE TO PRIVACY CONCERNS

MQTT_CLIENT_KEY = "private.pem.key"
MQTT_CLIENT_CERT = "certificate.pem.crt"
MQTT_BROKER = "endpoint"
MQTT_BROKER_CA = "AmazonRootCA1.pem"


def read_pem(file):
    with open(file, "r") as input:
        text = input.read().strip()
        split_text = text.split("\n")
        base64_text = "".join(split_text[1:-1])
        return ubinascii.a2b_base64(base64_text)


key = read_pem(MQTT_CLIENT_KEY)
cert = read_pem(MQTT_CLIENT_CERT)
ca = read_pem(MQTT_BROKER_CA)

mqtt_client = MQTTClient(
    MQTT_CLIENT_ID,
    MQTT_BROKER,
    keepalive=60,
    ssl=True,
    ssl_params={
        "key": key,
        "cert": cert,
        "server_hostname": MQTT_BROKER,
        "cert_reqs": ssl.CERT_REQUIRED,
        "cadata": ca,
    },
)

print(f"Connecting to MQTT broker")
blink_led()
mqtt_client.connect()
blink_led()

# Publishing part
while True:
    blink_led()
    distance_cm = int(random()*100)
    print(distance_cm)
    try:
        topic = "distance"
        payload = str(distance_cm)
        mqtt_client.publish(topic, payload)
        print(f"Published to {topic}: {payload}")
        blink_led()
    except Exception as e:
        print(f"Error publishing to MQTT: {e}")

I am trying to run my make a MQTT connection with my AWS IOT core so that I don't need any idle and can run it by just connecting my pi pico w to a power source. NOTE:I ALREADY SAVED MY PROGRAM AS main.py