★★★★ It may be that the previously installed office was not completely uninstalled. Use MicrosoftFixit, a special uninstall tool for office, to clean up the original office, or use Windows Install Clean, a self-produced uninstall software produced by Microsoft, to forcibly uninstall the originally installed office, delete all folders and files with office on drive C, and then clean up the garbage and lists.

★★★★ Delete the backup files left by the update (you can also use security guards or optimization software to slim down and delete the system).

This should be reinstallable.

★★★★ If not:

Run regedit to open the registry editor, find HKEY _ local _ machine \ software \ Microsoft \ Windows NT \ Current Version \ Image file execution options directory, and right-click the permission command: Look, if only read is checked, check full control permission, then click Add, enter your current system user name, click OK, and then check full control permission. Give it a try.