I can't combine unlock vbaproject and write in ThisWorkbook - vba

Question

Set wb = Workbooks(Filename)
Set codeModule = wb.VBProject.VBComponents("ThisWorkbook").codeModule
codeModule.InsertLines 3, "Hej jag kan spara detta"
wb.Save
Down below is my function. I want to unlock vbaproject and write in ThisWorkbook. For some reason when I incorporate the above 4 lines (at **), the workbook is not unlocked and the line "Hej jag kan spara detta" is not applied to ThisWorkbook. However, without these 4 rows, the workbook is unlocked. And if the workbook is unlocked before running the code, the same 4 lines also work. What is wrong?
Sub merniplusplus()
Dim path As String
Dim Filename As Variant
Dim wb As Workbook
Dim CodeModule As Variant
path = "C:\Merni\"
Filename = Dir(path & "*.xls")
Do While Filename <> ""
If Filename <> "merni.xlsm" Then
UnprotectPassword Workbooks(Filename), "2lbypo"
Set wb = ActiveWorkbook
Set CodeModule = wb.VBProject.VBComponents("ThisWorkbook").CodeModule
CodeModule.InsertLines 3, "Hej jag kan spara detta"
wb.Save
End If
Filename = Dir()
Loop
End Sub
Sub UnprotectPassword(wb As Workbook, ByVal projectPassword As String)
Dim currentActiveWb As Workbook
If wb.VBProject.Protection <> 1 Then
Exit Sub
End If
wb.Unprotect "poWorkbook"
Set currentActiveWb = ActiveWorkbook
wb.Activate
SendKeys "%{F11}"
SendKeys "^r" ' Set focus to Explorer
SendKeys "{TAB}" ' Tab to locked project
SendKeys "~" ' Enter
SendKeys projectPassword
SendKeys "~" ' Enter
If (wb.VBProject.Protection = vbext_pp_locked) Then
MsgBox ("failed to unlock")
End If
currentActiveWb.Activate
End Sub

Answer 1

Two things
Filename = Dir() should be before the loop and not before those 4 lines. Else you will get a different Filename.
Also the 4 lines should be inside your If Filename <> "merni.xlsm" Then Condition
Also you might want to close the workbook before you open the new one. Else you will have lot of workbooks open :)
FOLLOWUP
You are not opening the workbook but setting it to the current workbook every time and hence it is not working. I have tested the code below and it works just fine.
Sub merniplusplus()
Dim path As String, Filename As String
Dim wb As Workbook
Dim CodeModule As Variant
path = "C:\Merni\"
Filename = Dir(path & "*.xls")
Do While Filename <> ""
If Filename <> "merni.xlsm" Then
Set wb = Workbooks.Open(path & Filename)
UnprotectPassword wb, "2lbypo"
Set CodeModule = wb.VBProject.VBComponents("ThisWorkbook").CodeModule
CodeModule.InsertLines 3, "Hej jag kan spara detta"
wb.Close SaveChanges:=True
End If
Filename = Dir
Loop
End Sub