There should be any data in cell A1 in sheets(1) of workbook C:\Users\DJ-PC\PartDescriptions.xlsm
You should comment out or remove 'option explicit'.
I forgot a dot:

Sub M_snb() 
    With getobject("C:\Users\DJ-PC\PartDescriptions.xlsm") 
        sn = .Sheets(1).Cells(1).CurrentRegion
        .close 0 
    End With 
     
    With CreateObject("Powerpoint.application") 
        With .presentations.Add 
            For j = 1 To UBound(sn) 
                With .Slides.Add(1, 12) 
                    With .Shapes.AddTextbox(1, 120, 120, 270, 100).TextFrame.TextRange 
                        .Text = sn(j, 1) & vbLf & sn(j, 2) 
                        .Font.Size = 38 
                    End With 
                End With 
            Next 
        End With 
    End With 
End Sub