Question How do I enable a script/bool with a button?

Beginner so I might have missed something obvious.

https://gamedevbeginner.com/how-to-make-countdown-timer-in-unity-minutes-seconds/#timer

Currently have one script which I followed from GameDevBeginner (Link above) website to make a countdown timer, with the modifications being:

• The amount of time itself
• Setting the timer back to 5 on the 2nd else (which I assume runs every time the script is at the end)
• Extra progress float that I tried to make go up over time ( to link with the progress bar to represent the time going down ) which I think is working fine?

----------
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class Timer : MonoBehaviour
{
public float progress = 0;
public float timeRemaining = 5;
public bool timerIsRunning = false;
public Text timeText;
private void Start()
{

}
void Update()
{
if (timerIsRunning)
{
if (progress < 5)
{
progress += Time.deltaTime;
Debug.Log(progress);
}
else
{
progress = 0;
}

if (timeRemaining > 0)
{
timeRemaining -= Time.deltaTime;
DisplayTime(timeRemaining);
}
else
{
Debug.Log("Time has run out!");
timeRemaining = 5;
timerIsRunning = false;


}
}
}
void DisplayTime(float timeToDisplay)
{
timeToDisplay += 1;
float minutes = Mathf.FloorToInt(timeToDisplay / 60);
float seconds = Mathf.FloorToInt(timeToDisplay % 60);
timeText.text = string.Format("{0:00}:{1:00}", minutes, seconds);
}
}
-------

Everything works great except I don't have it running at the start of the game, I want it to run at the press of a button and reset itself once completed, but I can't seem to even get it to run on the button press.


This is the button which is imported from unity itself in the UI section. I tried to make the "On Click()" link to the "timerIsRunning" bool in the script ( to set it to true to make the script run ) which I could only have assumed was the Timer.enabled option since nothing else made sense.

But obviously this hasn't work and I've hit a dead end, any ideas or extra information needed?
(Please try to explain the simplest way you can, thanks!)

 

Is it maybe this?

Unity button onclick function script callback gameobject notes:

https://forum.unity.com/threads/onclick-no-functions-shown.669334/#post-7328488

For sliders and dropdowns and other value-returning UI elements:

https://forum.unity.com/threads/cant-return-a-value-for-drop-down-list.1171442/#post-7504738