Unfortunately, this does not seem to be doing anything:

Sub AddBorders()

        With Sheets("Shop Order")

        '  The following code works with page 2 of the shop order worksheet specifically with System B.
      
        '  In this first if statement, it is assumed that system B will not be in use at all.

            If .Range("A73") = "" Then
    
                .Range("C72:N74").Borders.LineStyle = 0              'this comment clears out all boxes for system B
    
            End If
     
        '  the following code creates one thick outline box because this carriage will have only one section.

    
            If .Range("A73") <> "" And Range("I46") = 1 Then
        
                .Range("E72:N74").Borders.LineStyle = 0           '  This line clears out all boxes for system B after the first carriage box
         
                With .Range("C72:D74")                            '  This line draws in 1 thick border box spanning two columns and three rows.
            
                 '  Remove all diagonal borders
                    .Borders(5).LineStyle = xlNone
                    .Borders(6).LineStyle = xlNone
                    .Borders(11).LineStyle = xlNone
                    .Borders(12).LineStyle = xlNone
                
                 '  Add borders around each cell
                    For i = 7 To 10
                        With .Borders(i)
                            .LineStyle = xlContinuous
                            .ColorIndex = 0
                            .TintAndShade = 0
                            .Weight = xlMedium
                        End With
                    Next i
                
                End With
        
            End If
            
        End With

End Sub
The above is in Module 3 and below is behind sheet1:

Private Sub Worksheet_Change(ByVal Target As Range)


If Target.Address = "$E$31" Then

    Call AddBorders                          'and this macro will actually be the code that you see creating the boxes with borders for sheet2 ("Shop Orders")

End If

End Sub