Set Search Results web part Fetched properties by PowerShell
Once we made typo in Core Search Results (SP 2010) web part in Fetched properties xml. This caused error of whole page (not only web part), so page was not editable any more and web part properties couldn't be edited any more via UI. SharePoint Designer also didn't allow to edit this page with web part. So we created following script to update Fetched properties value to correct xml and page was then editable again.