Android错误：java.lang.String类型的值<br不能转换为JSONObject

当前，我创建具有登录功能的应用程序。为了从android连接到MySQL数据库，我使用PHP。当我使用MySQLi时，一切正常。但是当我转换为PDO时，该错误将与我的问题的标题相同。谁能知道这是什么问题吗？以下是我的PHP代码：

    require_once 'configPDO.php';

    $response = array();

        if(isTheseParametersAvailable(array('badgeid', 'pwd'))){

            $badgeid = $_POST['badgeid'];
            $pwd = $_POST['pwd']; 

            $stmt = $conn->prepare("SELECT badgeid, email, fullname, roles_id, team_id FROM users WHERE badgeid = :badgeid AND pwd = :pwd AND roles_id = 3");
            // $stmt->bind_param("ss",$badgeid, $pwd);

            $stmt->bindParam(':badgeid',$badgeid,PDO::PARAM_STR);
            $stmt->bindParam(':pwd',$pwd,PDO::PARAM_STR);
            $stmt->execute();

            //$stmt->store_result();

            if($stmt->rowCount() > 0){

                $stmt->bindParam($badgeid, $email, $fullname, $roles_id, $team_id);
                $stmt->fetch();

                $user = array(
                    'badgeid'=>$badgeid, 
                    'email'=>$email,
                    'fullname'=>$fullname,
                    'roles_id'=>$roles_id,
                    'team_id'=>$team_id
                );

                $response['error'] = false; 
                $response['message'] = 'Login successfull'; 
                $response['user'] = $user; 
            }else{
                $response['error'] = false; 
                $response['message'] = 'Invalid username or password';
            }
        }
    echo json_encode($response);

    function isTheseParametersAvailable($params){

        foreach($params as $param){
            if(!isset($_POST[$param])){
                return false; 
            }
        }
        return true; 
    }