Admin Panel issue

1) Some files/folders may not have copied completely. Try a Manual Update: http://codex.wordpress.org/Updating_WordPress#Manual_Update

2) If that doesn’t help, use debug to find out if the issues are caused by PHP errors; you may have a theme or plugin conflict. See https://codex.wordpress.org/WP_DEBUG

Add

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false);

in wp-config.php and the debug.log file will be in wp-content.

Change the true to false, i.e.

define( 'WP_DEBUG_DISPLAY', false);

to dump errors to the browser, too.

3) If that doesn’t help, you can also try Using Your Browser to Diagnose JavaScript Errors.