Recoverable fatal error: Object of class User could not be converted to string in C: \ xampp \ htdocs \ iedan \ model \ UserDao.php on line 27

I get the following error:

  

Recoverable fatal error: Object of class User could not be converted to string in C: \ xampp \ htdocs \ iedan \ model \ Username.php on line 27.

I do not know what is due, here I leave the part of the code that throws me out of error

<?php 

include 'conexion.php';
include '../entidades/Usuario.php';


class UsuarioDao extends Conexion{
    protected static $cnx;

    public static function getConexion(){
        self::$cnx = Conexion::conectar();
    }

    private static function desconectar(){
        self::$cnx = null;
    }

//metodo para validar el login
    public static function login($usuario){

        $query = "SELECT id, nombre, usuario, email, privilegio, fecha_registro FROM usuarios WHERE usuario = :usuario AND password = :password";

        self::getConexion();

        $resultado = self::$cnx->prepare($query);

        $resultado->bindParam(":usuario", $usuario); //aqui esta el error
        $resultado->bindParam(":password", $password);

        $resultado->excecute();

        if(count($resultado)) {
            return true;
        }

        return false;

    }
}