Suspended.cgi = Non-payment. Once you update your billing information it should be active within the next 24 hours.
Error 500 = ICANN was not verified, therefore the domain is most likely suspended.
Check the email that was used when registering the domain to find the confirmation message.
DNS Failure = ICANN was not verified, therefore your domain is most likely suspended.
Contact your hosting provider and also check your inbox for any missed email updates.
ICANN stands for The Internet Corporation for Assigned Names and Numbers
ICANN, are the people in charge of regulating the internet and ensuring only real people own real sites and can keep track of everyone when a domain originates.
You will also receive an email with ICANN information and a link. You will need to click on that link to confirm that your email address is valid. If you don't click on that link, your domain will be suspended. So, please also check your spam/junk mail folders. If you cannot locate the email contact your hosting provider.