24 hour countdown timer in Unity3D

CountdownTimer.cs

using UnityEngine;
using TMPro;
using System;
using Microsoft.Unity.VisualStudio.Editor;
using UnityEngine.UI;
using UnityEngine.Events;

public class CountdownTimer : MonoBehaviour
{
    private int V = 1;
    public TextMeshProUGUI timerText;
    private DateTime startTime;
    private TimeSpan countdownDuration = TimeSpan.FromSeconds(6);
    private TimeSpan remainingTime;

    public UnityEngine.UI.Image radialFill;

    public UnityEvent doSomethingOnceTimerHitsZero;

    void Start()
    {
        // Load the saved start time from PlayerPrefs or initialize it if not saved yet
        if (PlayerPrefs.HasKey("StartTime"))
        {
            long savedTicks = Convert.ToInt64(PlayerPrefs.GetString("StartTime"));
            startTime = new DateTime(savedTicks);
        }
        else
        {
            startTime = DateTime.Now;
            PlayerPrefs.SetString("StartTime", startTime.Ticks.ToString());
            PlayerPrefs.Save();
        }

        // Calculate remaining time based on saved start time
        TimeSpan elapsedTime = DateTime.Now - startTime;
        remainingTime = countdownDuration - elapsedTime;

        // If remaining time is negative or greater than 24 hours, reset the timer
        // if (remainingTime.TotalHours <= 0 || remainingTime > countdownDuration)
        // {
        //     remainingTime = countdownDuration;
        //     startTime = DateTime.Now;
        //     PlayerPrefs.SetString("StartTime", startTime.Ticks.ToString());
        //     PlayerPrefs.Save();
        // }

        // Start the visual countdown
        UpdateVisualTimer();
    }

    void UpdateVisualTimer()
    {
        // Update the TMP text to display the remaining time
        timerText.text = string.Format("{0:D2}:{1:D2}:{2:D2}:{3:D3}", (int)remainingTime.TotalHours, remainingTime.Minutes, remainingTime.Seconds, remainingTime.Milliseconds);
        // radialFill.fillAmount = remainingTime.Seconds;
        float fillAmount = (float)remainingTime.TotalSeconds / (float)countdownDuration.TotalSeconds;
        radialFill.fillAmount = fillAmount;
    }

    void Update()
    {
        // if remaining time is negative or greater than countDownDuration, reset the timer
        if (remainingTime.TotalSeconds <= 0 || remainingTime > countdownDuration)
        {
            remainingTime = countdownDuration;
            startTime = DateTime.Now;
            PlayerPrefs.SetString("StartTime", startTime.Ticks.ToString());
            PlayerPrefs.Save();
        }
        // Update remainingTime every frame
        remainingTime = countdownDuration - (DateTime.Now - startTime);
        UpdateVisualTimer();

        // Do some Action when the timer hits zero.
        if (remainingTime.TotalSeconds <= 0)
        {
            doSomethingOnceTimerHitsZero.Invoke();
        }
    }

    public void Ass()
    {
        V = V + 1;
        Debug.Log("~~~~~~~~~~~~~~~~~~~~~~ TIMER HAS HIT ZERO " + "~~~~~~~~~~~~~~~~~~~~~~" + V);
    }

}