Te anexo una macro.
Instrucciones
1. Abre tu hoja de excel
2. Para abrir Vba-macros y poder pegar la macro, Presiona ALt + F11
3. En el menú elige Insertar / Módulo
4. En el panel del lado derecho copia la macro
5. Para ejecutarla presiona F5
'***Macro***
Sub bloqueacelda()
'Por.dam
'Cesbloquea hoja
Worksheets("Hoja4").Select
Cells.Select
Selection.Locked = False
Selection.FormulaHidden = False
Worksheets("Hoja5").Select
Cells.Select
Selection.Locked = False
Selection.FormulaHidden = False
Worksheets("Hoja6").Select
Cells.Select
Selection.Locked = False
Selection.FormulaHidden = False
Worksheets("Hoja2").Select
ufila = ActiveCell.SpecialCells(xlLastCell).Row
For i = 4 To ufila
If Cells(i, 9).Value = "SI" Then
Worksheets("Hoja4").Select
Cells(i, 5).Select
Cells(i, 5).Value = "No aplica"
Selection.Locked = True
Selection.FormulaHidden = False
Cells(i, 6).Select
Cells(i, 6).Value = "No aplica"
Selection.Locked = True
Selection.FormulaHidden = False
Worksheets("Hoja5").Select
Cells(i, 4).Select
Cells(i, 4).Value = "No aplica"
Selection.Locked = True
Selection.FormulaHidden = False
Worksheets("Hoja6").Select
Cells(i, 4).Select
Cells(i, 4).Value = "No aplica"
Selection.Locked = True
Selection.FormulaHidden = False
End If
Worksheets("Hoja2").Select
Next
Worksheets("Hoja4").Select
ActiveSheet.Protect DrawingObjects:=True, Contents:=True, Scenarios:=True
Worksheets("Hoja5").Select
ActiveSheet.Protect DrawingObjects:=True, Contents:=True, Scenarios:=True
Worksheets("Hoja6").Select
ActiveSheet.Protect DrawingObjects:=True, Contents:=True, Scenarios:=True
Worksheets("Hoja2").Select
End Sub
'***Macro***
Saludos.dam