One of the WordPress website hosted in our linux shared hosting was suspended due to payment pending. We activated the website after he paid. But when access the website its redirected to https://www.domain.com/cgi-sys/suspendedpage.cgi? and showing

Executing in an invalid environment for the supplied user 

We have tried the following to fix the error.

1. Upgrade/downgrade the hosting package

2. Created new Database user with all privileges and updated wp-config file

3. Changed the siteurl and home in PHPMyAdmin

I asked about this issue to our admin and he updated

Why the site is redirecting to HTTPS when site have no SSL installed ?

http://domain.com/license.txt working

http://domain.com/index.php redirecting, check the settings, see why it is redirecting.

Then I deactivated WordPress Plugins using PHPMyAdmin and website started to working.

I logged in the WordPress admin area and activated the plugins one by one.

When activating Really Simple SSL Plugin the error showing again. So deactivated the plugin and mail sent to customer to delete the plugin