I haven't looked at your workbooks, however you can use this in the Thisworkbook module (get there by pressing Alt+F11, right click thisworkbook view code then paste in).
 
Private Sub Workbook_BeforeClose(Cancel As Boolean)
    Dim MyCell As Range
    Dim Rng As Range
    Set Rng = Sheets("Sheet1").Range("A1:Z100") 'set your range
    For Each MyCell In Rng 'check each cell in that range
    If IsEmpty(MyCell) Then 'if it is empty
        MsgBox "Empty Cells exist" 'actions To Do If True
        MyCell.Select 'goto the offending cell
        Exit Sub
    End If
    Next
End Sub