Fatal error: Cannot redeclare zerif_setup() (previously declared in … function

your zerif-lite-child themes seems to be the error.

Repair or replace the /wp-content/themes/zerif-lite-child/functions.php file.

If you need immediate access to the dashboard, access your server via FTP/ SFTP , or a file manager in your hosting account’s control panel (consult your hosting provider’s documentation for specifics on these), navigate to /wp-content/themes/ and switch to the default theme by renaming your current theme’s folder by adding "-old" to the end of the folder name. Alternately, you can remove other themes except the default theme (Twenty Seventeen, etc.). That will force your site to use it.

read https://codex.www.ads-software.com/Child_Themes#Using_functions.php

Do not copy the full content of functions.php of the parent theme into functions.php in the child theme.

to get your site working again, try and use FTP https://codex.www.ads-software.com/FTP_Clients to remove the content of functions.php in the child theme.

if you are trying to use functions.php to change something in your child theme, please post the question in your parent theme’s forum at https://www.ads-software.com/support/theme/zerif-lite

Thank you very very much!!!!!!!