Hello BSullivan,
We are aware of this issue where customers are getting error 504 (Bad Gateway) when attempting to log into their QuickBooks Online account. We are currently working on to get it fixed as soon as possible.
Thank you for your patience as we work through this. You can also follow this link to subscribe for the updates: http://status.quickbooks.intuit.com/incidents/gth329fb8w4z.
We're always here if you need anything else with your account.
