Arduino Serial Communication with Raspberry PI Issue

My raspberry pi is not receiving or not reading serial data from a connected Arduino. My Arduino is set to collect pressure and temperature data at 1-hour intervals and send it over serial port. The raspberry pi should listen for the data and write it to a file. I have it setup so that if the raspberry pi does not receive any data within an hour, it resets itself and writes error code to a file. My current setup resets itself every hour. Before I added the reset it would just not save anything for hours on end. The Arduino is connected to the raspberry pi via usb port.

Arduino Code

#include <LiquidCrystal_I2C.h>  //allows interfacing with LCD screens

#include "max6675.h"
int ktcSO = 4;
int ktcCS = 5;
int ktcCLK = 6;
MAX6675 ktc(ktcCLK, ktcCS, ktcSO);

const int pressureInput0 = A0, pressureInput1 = A1, pressureInput2 = A2, pressureInput3 = A3 ;     //Select the analog input pin for the pressure transducer
float pressureValue0 = 0, pressureValue1 = 0, pressureValue2 = 0, pressureValue3 = 0 ;             //Variable to store the value coming from the pressure transducer

const int pressureZero = 102.3;                 //Analog reading of pressure transducer at 0psi
const int pressureMax = 920.7;                  //Analog reading of pressure transducer at MAX psi
const int pressuretransducermaxPSI = 2500;      //psi value of transducer being used
const int sensorreadDelay = 1000;               //Constant integer to set the sensor read delay in milliseconds

long Timer = 0;

LiquidCrystal_I2C lcd(0x27, 20, 4);             //Sets the LCD I2C communication address; format(address, columns, rows)

void setup() {
  lcd.init();                   // Initiate the LCD:
  lcd.backlight();              // Initiate the LCD:
  delay(3500);                  // Wait for RasPi

void loop() {
  lcd.setCursor(13, 0);
  lcd.print(" C");

  float Pressure0 = printPressure(pressureValue0, pressureInput0, 0, 9.17);
  float Pressure1 = printPressure(pressureValue1, pressureInput1, 1, 9.17);
  float Pressure2 = printPressure(pressureValue2, pressureInput2, 2, 9.17);
  float Pressure3 = printPressure(pressureValue3, pressureInput3, 3, 9.17);

  if (Timer <= 0) {  //If time to next read 
    Serial.print(Pressure0); Serial.print(","); Serial.print(Pressure1); Serial.print(","); Serial.print(Pressure2);
    Serial.print(","); Serial.print(Pressure3); Serial.print(","); Serial.println(ktc.readCelsius());
    Timer = 3600000;  //Wait 1 hour
  delay(sensorreadDelay);         //Delay in milliseconds between read values
  Timer -= sensorreadDelay;

float printPressure (float pressureValue, int pressureInput, int cursorLocation, float offSet) {
  lcd.setCursor(0, cursorLocation);
  pressureValue = analogRead(pressureInput);      //Reads value from input pin and assigns to variable
  pressureValue = ((pressureValue - pressureZero) * pressuretransducermaxPSI) / (pressureMax - pressureZero) + offSet;

  return pressureValue;

Raspberry Pi Python Code

#!/usr/bin/env python3
import serial
import datetime
import time
import os

if __name__ == '__main__':
    ser = serial.Serial('/dev/ttyACM0', 9600, timeout=1)
    date =
    delay = 3610
    waitTime = delay
    while True:
            if ser.in_waiting > 0:
                file = open("/home/pi/MEGA/Python_Script/Save.txt", "a")
                date =
                line = ser.readline().decode('utf-8').rstrip()
                file.write(date.strftime("%m-%d-%Y,%H:%M:%S," + line + '\n'))
                print(date.strftime("%m-%d-%Y,%H:%M:%S," + line + '\n'))
                waitTime = delay
            if waitTime == 0:
                file = open("/home/pi/MEGA/Python_Script/ErrorLogSB.txt", "a")
                file.write(date.strftime("Time Out " + "%m-%d-%Y,%H:%M:%S," + '\n'))
                os.system('sudo shutdown -r now')
            waitTime -= 1
            file = open("/home/pi/MEGA/Python_Script/ErrorLogSB.txt", "a")
            file.write(date.strftime("Other Error " + "%m-%d-%Y,%H:%M:%S," + '\n'))
            os.system('sudo shutdown -r now')```