Backup failed, now site completely down with “maintenance” page showing

Paid user. I began a restore yesterday and received an error message, the backup was unable to complete, please allow 6 4 4 file permissions to the stored backup file (obviously theres something wrong already). I made sure file permissions were set correctly for the specified file. Still no luck. Now my site is showing the “Briefly unavailable for scheduled maintenance” page and now im unable to even access the wp dashboard. Im locked out. Could you please lead me through the best way to manually repair the site using ftp?