Hey Jonathan Just Tell Me How to Find Control inside Of DataGrid Header Column

Here is My XAML Code

<navigation:Page x:Class="CheckBoxDemo.Views.MyPages.CheckBoxDemo"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x=http://schemas.microsoft.com/winfx/2006/xaml

xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

mc:Ignorable="d"

xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"

xmlns:dg="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data"

d:DesignWidth="640" d:DesignHeight="480"

xmlns:dataprimitives="clr-namespace:System.Windows.Controls.Primitives;assembly=System.Windows.Controls.Data"

Title="CheckBoxDemo Page" Loaded="Page_Loaded">

<dg:DataGridTemplateColumn Width="auto">

<dg:DataGridTemplateColumn.HeaderStyle>

<Style TargetType="dataprimitives:DataGridColumnHeader">

<Setter Property="ContentTemplate">

<Setter.Value>

<DataTemplate>

<CheckBox Content="Select Location" IsChecked="{Binding IsSelected, Mode=TwoWay}" x:Name="chkSelectAll" Checked="chkSelectAll_Checked" Unchecked="chkSelectAll_Unchecked"></CheckBox>

</DataTemplate>

</Setter.Value>

</Setter>

</Style>

</dg:DataGridTemplateColumn.HeaderStyle>

<dg:DataGridTemplateColumn.CellEditingTemplate>

<DataTemplate>

<CheckBox x:Name="chksSelected" IsChecked="{Binding IsSelected, Mode=TwoWay}" Width="100"VerticalAlignment="Center"/>

</DataTemplate>

</dg:DataGridTemplateColumn.CellEditingTemplate>

</dg:DataGridTemplateColumn>

Now i want to UnCheck that CheckBox located in DataGrid Header on Click Of Button How i can Achieve these Functionality

Any Help Would Be Appreciated