Using a timer in conjunction with two push buttons from Arduino input

Hello all, noob here

So I am using two push buttons (connected to an Arduino Uno) as an input to my game. The player has to push down both buttons at the same time for the character to move in the game. I want the player to hold down the buttons for a different amount of time in each level. I have a working Arduino and a working Unity timer and player script, but am not able to get the code to do what I want. What I basically want is that only when the player presses the buttons down, does the timer start counting down. Right now, the timer starts as soon as the scene begins. I know that I somehow have to reference the timer script to the button object, I have tried this but it still doesn't work. Note that the timer UI does have a Timer tag on it. Right now, the timer just doesn't count down at all. Please help

Timer script:

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 using UnityEngine.SceneManagement;
 
 public class Timer : MonoBehaviour
     {
         public int timeLeft;
         public Text countdownText;
         private bool timerStarted;
 
     public void BeginTimer()
     {
 
     }
 
     public void BeginTimer(int seconds) 
         {
         // Here you have to decide whether you want to restart a timer
 
         timeLeft = seconds;
         // or if you rather want to continue counting down
         if (!timerStarted)
         {
             timeLeft = seconds;
 
             StartCoroutine(LoseTime());
         }
         }
 
         public void StopTimer()
         {
             StopAllCoroutines();
         }
     void Update()
     {
         countdownText.text = ("Time Left = " + timeLeft);
 
         if (timeLeft <= 0)
         {
 
             Invoke("ChangeLevel", 0.1f);
         }
     }
 
         private IEnumerator LoseTime()
         {
             timerStarted = true;
         
 
         while (true)
             {
                 yield return new WaitForSeconds(1);
                 timeLeft--;
             //countdownText.text = ("Time Left = " + timeLeft);
             //countdownText.text = $"Time Left = {timeLeft}";
         }
 
         //Invoke("ChangeLevel", 0.1f);
         //Invoke(nameof(ChangeLevel), 0.1f);
         }
 
         void ChangeLevel()
         {
             SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 1);
         }
     }

Player script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System.IO.Ports;
 using UnityEngine.UI;
 
 public class PlayerController : MonoBehaviour
 {
     public float Speed;
     public Vector2 height;
     public float xMax, xMin, yMin, yMax;
     public bool buttonPressed = false;
 
     public Rigidbody2D Character;
     public Timer timer;
     public Rigidbody2D _rigidbody;
 
     private SerialPort sp = new SerialPort("\\\\.\\COM4", 9600);
 
     private void Awake()
     {
         FetchReferences();
     }
 
     [ContextMenu("FetchReferences")]
     private void FetchReferences()
     {
         if (!Character) Character = GameObject.FindWithTag("Player").GetComponent<Rigidbody2D>();
         if (!timer) timer = GameObject.Find("Timer").GetComponent<Timer>();
     }
 
     private void Start()
     {
         if (!sp.IsOpen)
         {
             sp.Open(); // Open 
         }
         sp.ReadTimeout = 1;
     }
 
     private void Update()
     {
        if (sp.IsOpen)
         {
             try
             {
 
                 string value = sp.ReadLine(); //Read the information
                 int button = int.Parse(value);
 
                 if (button == 0) //*Input.GetKeyDown(KeyCode.Space*/)  //jump
                 {
                     buttonPressed = true;
 
                     Character.GetComponent<Rigidbody2D>().AddForce(height, ForceMode2D.Impulse);
 
                     
 
                     timer.BeginTimer();
                 }
                 else
                 {
                     
                     timer.StopTimer();
                 }
             }
             catch (System.Exception)
             {
                
             }
         }
     }
 
 
     private void FixedUpdate()
     {
         Character.position = new Vector3
                     (
                         Mathf.Clamp(GetComponent<Rigidbody2D>().position.x, xMin, xMax),
                         Mathf.Clamp(GetComponent<Rigidbody2D>().position.y, yMin, yMax)
                     );
         //Character.position = new Vector3(Mathf.Clamp(Character.position.x, Min.x, Max.x), Mathf.Clamp(Character.position.y, Min.y, Max.y));
     }
 
     
     private void ApplicationQuit()
     {
         if (sp != null)
         {
             {
                 sp.Close();
             }
         }
     }
 }

Please assist; no errors this far