I suppose it’s possible. Sometimes those security plugins freak out when the domain changes.
It might be another plugin or theme that is causing things to break. I’ve mostly only seen that
Duplicate Key error with WordFence, but in theory anything could break in that same way.
That’s not a bad idea. If all you are interested in are the posts, you might try using WordPress’ built in exporter: https://codex.wordpress.org/Tools_Export_Screen – This creates an xml file of the various posts and allows you to import those posts using the Import screen: https://codex.wordpress.org/Tools_Import_Screen
This has sometimes been buggy depending on what kind of content is contained within the posts, but it might be worth a try.
As for the white screen – that’s usually a theme issue. Are you able to login to the
wp-admin of the site? You might also be able to get more errors displaying by enabling
WP_DEBUG in the
wp-config.php file. See the codex for more information about that: https://codex.wordpress.org/Debugging_in_WordPress
Let us know if you get any more meaningful errors when enabling