WordPress admin not loading css/js

Are there errors in the browser console?

Learn to use the Chrome Developer Tools or Firefox Developer Tools.

“only one instance of babel”. Are you using a plugin or theme that uses that? This may be a plugin or theme conflict. Please attempt to disable all plugins, and use one of the default (Twenty*) themes. If the problem goes away, enable them one by one to identify the source of your troubles.

If you can install plugins, install “Health Check”: https://ww.wp.xz.cn/plugins/health-check/ On the troubleshooting tab, you can click the button to disable all plugins and change the theme for you, while you’re still logged in, without affecting normal visitors to your site. You can then use its admin bar menu to turn on/off plugins and themes one at a time.

See http://www.wpbeginner.com/plugins/how-to-deactivate-all-plugins-when-not-able-to-access-wp-admin/