Checking if Button is not pressed

I am making a Shield for my 2D game and I enable it as soon as I press “Fire2”, however it does not get disabled after I let go of the button. I have tried to use an else command to disable it, but I cannot get Unity to detect me leaving the button. Here is the code, please help!

void Shield()
    {
        if(Input.GetButtonDown("Fire2"))
        {
            Shield1.SetActive(true);
            
        } 
        

     //This Does Not Work
        if(Input.GetButtonUp("Fire2"))
        {
            Shield1.SetActive(false);
        }
    }

I would use “!” instead of using “GetButtonUp” So instead of reading:

 void Shield()
     {
         if(Input.GetButtonDown("Fire2"))
         {
             Shield1.SetActive(true);
             
         } 
         
 
      //This Does Not Work
         if(Input.GetButtonUp("Fire2"))
         {
             Shield1.SetActive(false);
         }
     }

It could read:

 void Shield()
     {
         if(Input.GetButtonDown("Fire2"))
         {
             Shield1.SetActive(true);
             
         } 
         else if(!Input.GetButtonDown("Fire2"))
         {
             Shield1.SetActive(false);
         }
     }