Hi devil495,
If you renamed the wp-content/plugins/updraftplus directory, and if you cannot login via the dashboard (use the /wp-admin link, not one via a front-end page) then your problem must lie somewhere else. Once you rename a plugin, the WordPress admin application doesn't (and indeed, can't) run any code from that plugin any more. So if you're still getting errors on an admin (wp-admin) login after that, then you have a different problem.
I'd suggest trying to find out where your PHP logs are (ask your web hosting company), so that you can see what is being logged on the server side as the error when the front-end shows the 500.
David