Private Sub CommandButton3_Click()
Dim XLP As Workbook
Set XLP = Workbooks.Open("C:\DOCM\пко_клиент.xlsx")
With XLP.Application
.Visible = False   
.ScreenUpdating = False    
.DisplayAlerts = False     
.EnableEvents = False       

'код..............

.Workbooks("пко_клиент.xlsx").Close True
End With

Workbook("ПКО.xlsm").Activate = True  'так не получается
Workbook("ПКО.xlsm").Visible = True
MsgBox "сообщение"
End Sub

Windows("ПКО.xlsm").Visible = True

Workbooks("ПКО.xlsm").Visible = True

Dim xl_p As Workbook
Set xl_p = Workbooks("ПКО.xlsm")

xl_p.Application.Visible = True