Help! GSM/GPRS/GNSS HAT - SIM 868

Question

have be struggling for a while with this bit of Python. I have not wrote this code it got installed with the the tracker from this website (https://medium.com/@onehitwonder/how-to-build-a-raspberry-pi-gps-tracker-c5e63d456c84)So what's not working it the sending and receiving of the text message with the GPS location, I know its the python code as when I run minicom all the commands work. When I run this in Thonny I do get lots of errors, I have been trying to fix them but my knowledge in python is very limited.

What should happen is when I text (start) to the SIM in the tracker it should send a Google GPS back to my number.

Could anyone please spot the mistakes and help me to get this working please?

Here the tracker.py in current state:

import time
import math
import sys
from pygsm import GsmModem

# Switch GPS on
def SwitchGPSon():
    print ("Switching GPS on ...")
    reply = gsm.command('AT+CGNSPWR=1')
    print(reply)
    print

def SwitchGPSoff():
    print ("Switching GPS off ...")
    reply = gsm.command('AT+CGNSPWR=0')
    print(reply)
    print
    
def SendGPSPosition():
    print ("Getting GPS position ...")
    reply = gsm.command('AT+CGNSINF')
    list = reply[0].split(",")
    UTC = list[2][8:10]+':'+list[2][10:12]+':'+list[2][12:14]
    Latitude = list[3]
    Longitude = list[4]
    Altitude = list[5]
    print ('Position: ' + UTC + ', ' + Latitude + ', ' + Longitude + ', ' + Altitude)
    # Text to mobile
    Message = ' Position: ' + UTC + ', ' + str(Latitude) + ', ' + str(Longitude) + ', ' + str(Altitude) + ' http://maps.google.com/?q=' + str(Latitude) + ',' + str(Longitude)
    print ("Sending to mobile" + MobileNumber + ": " + Message)
    gsm.send_sms(MobileNumber, Message)


# Set mobile number here
MobileNumber = "0795071****"
lastmessage = 'Stop'

print ("Booting modem ...")
gsm = GsmModem(port="/dev/ttyS0")
gsm.boot()

print ("Modem details:")
reply = gsm.hardware()
print ("Manufacturer = " + reply['manufacturer'])
print ("Model = " + reply['model'])

# Try and get phone number
reply = gsm.command('AT+CNUM')
if len(reply) > 1:
    list = reply[0].split(",")
    phone = list[1].strip('\"')
    print ("Phone number = " + phone)
print
    
print ("Deleting old messages ...")
gsm.query("AT+CMGD=70,4")
print

SwitchGPSon()

print ("Boot successful, waiting for messages ...")

while True:
        
    # Check messages
    message = gsm.next_message()
    
    if message:
        print ("loop 1")
        print (message)
        text = message.text
        if text[0:5] == 'Start':
            print ("Start sending Position ...")
            SendGPSPosition()
            lastmessage = 'Start'
            time.sleep(300)
        elif text[0:4] == 'Stop':
            print ("Text was Stop. Stop sending")
            lastmessage = 'Stop'
    else:
        if lastmessage == 'Start':
            print(lastmessage+' loop2')
            SendGPSPosition()
            time.sleep(300)
        else:
            time.sleep(10)