Adding A File Path From A Dialog Box Selection

I am trying to white a macro that takes a file path from a cell value and opens that file. When there is no file path in the cell, it prompts a dialog box. This part is pretty much working. However, I would like the file path selected from the dialog box to be added to the cell in the original workbook.

Sub Reports()
Dim path1 As String
path1 = Range("B20").Value
On Error Resume Next
'checks if there is already a file path'
Workbooks.Open filename:= _
path1, Updatelinks:=1
'if no file path then opens dialog box'
If Error.Number <> 0 Then
Application.Dialogs(xlDialogOpen).Show Arg1:="*.*"

End If
End Sub