If you're getting ERR_TOO_MANY_REDIRECTS then something is not correctly set on your site i.e. it usually happens when the redirect is not set correctly or some plugin/module is the culprit such as SEO/pretty URL is active by some plugin/module which is creating an issue with redirects or the issue is coming from some URL redirect plugin/module.
To solve the issue try disabling any redirect plugin/module you've installed for your website and check if your website is loading fine or not.
If it still doesn't solved alternatively you can also try to add this .htaccess rule by removing/replacing current http-https redirect rule from .htaccess :
SetEnvIf X-Forwarded-Proto "https" HTTPS=on
RewriteEngine on
RewriteCond %{HTTPS} !=on
RewriteCond %{HTTP:X-Forwarded-Proto} !https [NC]
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]