Unable to open PlugIn throug wp-admin/ as administrator.

I would certainly recommend activating WP_DEBUG as it could outcome the real mistake after that so it can direct you in the ideal instructions. https://wordpress.org/support/article/debugging-in-wordpress/

If you can set up plugins (Plugins > > Include New) after that you can attempt the WP Debugging plugin on the repo to attempt to do this for you.

You can likewise consult your web server error_log as the mistake could turn up therein.

If you do locate a real mistake in web server error_log or from allowing WP_DEBUG as well as you’re unsure what it implies, you can publish it below as well as we can attempt to assist even more