Unfortunately you found this post. That means you must meet some trouble like as I met before. The tricky issue is your wp-admin of WordPress will be traped into a redirect loop until browser show an error called
Let’s leave the root cause behind first and give you the answer that you could try to resolve this issue.
Generally, facing the issues related with SSL certificate you can through these two ways to solve it:
(1) Modify the URL settings in database.
(2) Adjust the
.htaccess to make a permanent redirect to https URL.
But if you can’t end up loop of redirect, I recommend that you can try this way.
wp-config.php in your WordPress folder, and add this paragraph at the tail of code. It should let your website back online.
/** SSL */
// in some setups HTTP_X_FORWARDED_PROTO might contain
// a comma-separated list e.g. http,https
// so check for https existence
if (strpos($_SERVER['HTTP_X_FORWARDED_PROTO'], 'https') !== false)