Check the wp-options table and fix the two URLs in there to your site’s URLs. Then remove the URLs you added to the wp-config.php file. (That setting in the wp-config.php file overrides the wp-options table, but I don’t recommend that way of setting up the site URLs – set the URLs in teh wp-options table. (That won’t fix the problem, it’s just a better way to set up the URLs, IMHO.)
Then, take a look at the error.log file. That’s going to tell you why you got a white screen. Post that here as an added part to your question. Without the error message, it’s just a guessing game. Renaming the plugins folder is a start. You could also rename the active theme’s folder, which will force WP to use one of the ‘twenty’ themes.
ALso, take a look at your htaccess file for the old URL.
But the error.log file is the file that you need to look at for clues to your issue.
When you get it all working, use a Search and Replace plugin to change all old URLs to the new one. (I like the ‘Better Search and Replace’ plugin.) Media entries have the URL ‘inside’, so you have to change them.
Once you get all working again, and fix all URLs, use the Network tab of the Inspector (F12) to check all requests for the proper URL.