Please help us help you and fill where relevant:
Your LimeSurvey version: 5.4.15+
Own server or LimeSurvey hosting: shared hosting through Canadian Web hosting
Survey theme/template: unknown
==================
I followed the prompts to install the security update, generated a ComfortUpdate token, and followed the process. At the end of the process, there was an error, which I figured would just kick me back to the admin interface. Since then, the site only loads a blank white screen.
surveys.otessa.org
I have backups but can't even access the admin interface to use them.
Help?

Colin

otessa wrote:

I have backups but can't even access the admin interface to use them.
 

The backups of files and database are needed in case the admin interface of LimeSurvey is no longer accessible.
In LimeSurvey you can only download the complete database as a file.
And you will need to restore the database manually.

First I would access the home directory of you website where LimeSurvey is installed.
Perhaps there is only a small issue and everything is still there.
I recommend to backup everything in the directories there first.