I am another staff checking in.
I am still seeing an error 500.
Usually an error 500 means that there is a fatal error. It could be a broken code or a PHP memory limit exhaustion. Could you please enable the Debug mode? You can do this by opening wp-config.php and adding
/* That's all, stop editing! Happy blogging. */
When you revisit the page, you should have some error output describing the issue in more detail. Meanwhile, we recommend that you increase your memory allocated to PHP. To increase it, please edit your wp-config.php file and insert these lines:
define( 'WP_MEMORY_LIMIT', '256M' );
define( 'WP_MAX_MEMORY_LIMIT', '512M' );
You can add it before the line
/*That's all, stop editing! Happy Blogging. */
We would loved to know if this has work for you. Thank you.