how to make it die and make it permanent(true)?

how to make a player die at health 0 ?

how to make (visible) to be permanent (true)

I have scripts ...

and the script are still many bugs .. (did not die at health 0) and other

I want to change (Visible) becomes permanent (true) and does not change the core script, and the player has a health 0, the player will die, and the display my scary picture for a few seconds with sound , and return to the main menu

This is my script, need help,Help me upgrade it ...

 #pragma strict
 @script RequireComponent( AudioSource )
 
 public var thePlayer : Transform;
 private var theEnemy : Transform;
 
 public var speed : float = 5.0;
 
 var isOffScreen : boolean = false;
 public var offscreenDotRange : float = 0.7;
 
 var isVisible : boolean = true;
 public var visibleDotRange : float = 0.8; // ** between 0.75 and 0.85 (originally 0.8172719) 
 
 var isInRange : boolean = false;
 
 public var followDistance : float = 24.0;
 public var maxVisibleDistance : float = 25.0;
 
 public var reduceDistAmt : float = 3.1;
 
 private var sqrDist : float = 0.0;
 
 public var health : float = 100.0;
 public var damage : float = 20.0;
 
 public var enemySightedSFX : AudioClip;
 
 private var hasPlayedSeenSound : boolean = false;
 
 private var colDist : float = 5.0; // raycast distance in front of enemy when checking for obstacles
 
 
 function Start() 
 {
     if ( thePlayer == null )
     {
         thePlayer = GameObject.Find( "Player" ).transform;
     }
     
     theEnemy = transform;
 }
 
 function Update() 
 {
     // Movement : check if out-of-view, then move
     CheckIfOffScreen();
     
     // if is Off Screen, move
     if ( isOffScreen )
     {
         MoveEnemy();
         
         // restore health
         RestoreHealth();
     }
     else
     {
         // check if Player is seen
         CheckIfVisible();
         
         if ( isVisible )
         {
             // deduct health
             DeductHealth();
             
             // stop moving
             StopEnemy();
             
             // play sound only when the Man is first sighted
             if ( !hasPlayedSeenSound )
             {
                 audio.PlayClipAtPoint( enemySightedSFX, thePlayer.position ); 
             }
             hasPlayedSeenSound = true; // sound has now played
         }
         else
         {
             // check max range
             CheckMaxVisibleRange();
             
             // if far away then move, else stop
             if ( !isInRange )
             {
                 MoveEnemy();
             }
             else
             {
                 StopEnemy();
             }
             
             // reset hasPlayedSeenSound for next time isVisible first occurs
             hasPlayedSeenSound = false;
         }
     }
     
 }
 
 
 function DeductHealth() 
 {
     // deduct health
     health -= damage * Time.deltaTime;
     
     // check if no health left
     if ( health <= 0.0 )
     {
         health = 0.0;
         Debug.Log( "YOU ARE OUT OF HEALTH !" );
         
         // Restart game here!
         // Application.LoadLevel( "sceneLose" );
     }
 }
 
 
 function RestoreHealth() 
 {
     // deduct health
     health += damage * Time.deltaTime;
     
     // check if no health left
     if ( health >= 100.0 )
     {
         health = 100.0;
         //Debug.Log( "HEALTH is FULL" );
     }
 }
 
 
 function CheckIfOffScreen() 
 {
     var fwd : Vector3 = thePlayer.forward.normalized;
     var other : Vector3 = (theEnemy.position - thePlayer.position).normalized;
     
     var theProduct : float = Vector3.Dot( fwd, other );
     
     if ( theProduct < offscreenDotRange )
     {
         isOffScreen = true;
     }
     else
     {
         isOffScreen = false;
     }
 }
 
 
 function MoveEnemy() 
 {
     // Check the Follow Distance
     CheckDistance();
     
     // if not too close, move
     if ( !isInRange )
     {
         rigidbody.velocity = Vector3( 0, rigidbody.velocity.y, 0 ); // maintain gravity
         
         // --
         // Old Movement
         //transform.LookAt( thePlayer );        
         //transform.position += transform.forward * speed * Time.deltaTime;
         // --
         
         // New Movement - with obstacle avoidance
         var dir : Vector3 = ( thePlayer.position - theEnemy.position ).normalized;
         var hit : RaycastHit;
         
         if ( Physics.Raycast( theEnemy.position, theEnemy.forward, hit, colDist ) )
         {
             //Debug.Log( " obstacle ray hit " + hit.collider.gameObject.name );
             if ( hit.collider.gameObject.name != "Player" && hit.collider.gameObject.name != "Terrain" )
             {            
                 dir += hit.normal * 20;
             }
         }
     
         var rot : Quaternion = Quaternion.LookRotation( dir );
     
         theEnemy.rotation = Quaternion.Slerp( theEnemy.rotation, rot, Time.deltaTime );
         theEnemy.position += theEnemy.forward * speed * Time.deltaTime;
         //theEnemy.rigidbody.velocity = theEnemy.forward * speed; // Not Working
         
         // --
     }
     else
     {
         StopEnemy();
     }
 }
 
 
 function StopEnemy() 
 {
     transform.LookAt( thePlayer );
     
     rigidbody.velocity = Vector3.zero;
 }
 
 
 function CheckIfVisible() 
 {
     var fwd : Vector3 = thePlayer.forward.normalized;
     var other : Vector3 = ( theEnemy.position - thePlayer.position ).normalized;
     
     var theProduct : float = Vector3.Dot( fwd, other );
     
     if ( theProduct > visibleDotRange )
     {
         // Check the Max Distance
         CheckMaxVisibleRange();
         
         if ( isInRange )
         {
             // Linecast to check for occlusion
             var hit : RaycastHit;
             
             if ( Physics.Linecast( theEnemy.position + (Vector3.up * 1.75) + theEnemy.forward, thePlayer.position, hit ) )
             {
                 Debug.Log( "Enemy sees " + hit.collider.gameObject.name );
                 
                 if ( hit.collider.gameObject.name == "Player" )
                 {
                     isVisible = true;
                 }
             }
         }
         else
         {
             isVisible = false;
         }
     }
     else
     {
         isVisible = false;
     }
 }
 
 
 function CheckDistance() 
 {
     var sqrDist : float = (theEnemy.position - thePlayer.position).sqrMagnitude;
     var sqrFollowDist : float = followDistance * followDistance;
     
     if ( sqrDist < sqrFollowDist )
     {
         isInRange = true;
     }
     else
     {
         isInRange = false;
     }    
 }
 
 
 function ReduceDistance() 
 {
     followDistance -= reduceDistAmt;
 }
 
 
 function CheckMaxVisibleRange() 
 {
     var sqrDist : float = (theEnemy.position - thePlayer.position).sqrMagnitude;
     var sqrMaxDist : float = maxVisibleDistance * maxVisibleDistance;
     
     if ( sqrDist < sqrMaxDist )
     {
         isInRange = true;
     }
     else
     {
         isInRange = false;
     }    
 }
 
 
 function OnGUI()
 {
     GUI.Box( Rect( (Screen.width * 0.5) - 60, Screen.height - 35, 120, 25 ), "Health : " + parseInt( health ).ToString() );
 }