Trying to establish turn order in my game but bool will not toggle properly

I'm trying to make it so that when the game begins it is the brown team's turn ("brownTurn = true;"), but when a successful "ValidMove" is performed, the "brownTurn" bool is toggled, creating the turn order. However, with what I currently have, "brownTurn" seems to always stay at whatever it is set to in the void start and I'm not sure why. Any suggestions?

 public class Piece : MonoBehaviour {
 
     public int pieceType;
     public string team;
     public int rotation;
 
     public bool isBrown;
     public bool isGreen;
 
     public bool brownTurn;
 
     private void Start()
     {
         brownTurn = false;
     }
 
 
     public bool ValidMove(Piece[,] Board, int x1, int y1, int x2, int y2)
     {
         // if your're moving on top of another piece 
         if (Board[x2, y2] != null)
             return false;
 
         int deltaMove = Mathf.Abs(x1 - x2);
         int deltaMoveY = y2 - y1;
 
         if (brownTurn)
         {
             if (isBrown)
             {
                 if (pieceType == 3)
                 {
                     if (deltaMove <= 2 && deltaMove >= -2)
                     {
                         if (deltaMoveY <= 2 && deltaMoveY >= -2)
                         {
                             //Piece p = Board[(x1 + x2) / 2, (y1 + y2) / 2];
                             //if (p != null)
                             return true;
                         }
                     }
                 }
                 if (pieceType == 2)
                 {
                     if (deltaMove <= 2 && deltaMove >= -2)
                     {
                         if (deltaMoveY <= 2 && deltaMoveY >= -2)
                             return true;
                     }
                 }
 
                 if (pieceType == 1)
                 {
                     if (deltaMove == 1 || deltaMove == -1)
                     {
                         if (deltaMoveY == 1 || deltaMoveY == -1)
                             return true;
                     }
                 }
                 if (pieceType == 0)
                 {
                     if (deltaMove <= 3 && deltaMove >= -3)
                     {
                         if (deltaMoveY <= 3 && deltaMoveY >= -3)
                             return true;
                     }
                 }
 
                 brownTurn = false;
             }
         }
 
         if (!brownTurn)
 
             if (isGreen)
             {
                 if (pieceType == 3)
                 {
                     if (deltaMove <= 2 && deltaMove >= -2)
                     {
                         if (deltaMoveY <= 2 && deltaMoveY >= -2)
                         {
                             //Piece p = Board[(x1 + x2) / 2, (y1 + y2) / 2];
                             //if (p != null)
                             return true;
                         }
                     }
                 }
                 if (pieceType == 2)
                 {
                     if (deltaMove <= 2 && deltaMove >= -2)
                     {
                         if (deltaMoveY <= 2 && deltaMoveY >= -2)
                             return true;
                     }
                 }
                 if (pieceType == 1)
                 {
                     if (deltaMove == 1 || deltaMove == -1)
                     {
                         if (deltaMoveY == 1 || deltaMoveY == -1)
                             return true;
                     }
                 }
                 if (pieceType == 0)
                 {
                     if (deltaMove <= 3 && deltaMove >= -3)
                     {
                         if (deltaMoveY <= 3 && deltaMoveY >= -3)
                             return true;
                     }
                 }
 
                 brownTurn = true;
             }
 
         return false;
 
     }
 
     //private void whoseTurn(bool isTurnOne)
     //{
     //    isTurnOne = !isTurnOne;
     //}
 
 }