First of all, again, thank you for backing Original Sin!
1) Currently, there are issues with non-working kickstarter codes. If your code is currently not working, please keep an eye on this post or on the latest kickstarter update. We are working on the issue and will have a fix very soon (update is uploading now)
2) If you are still having kickstarter code issues by tomorrow, please shoot an email to kickstarter@larian.com with a clear explanation of your issue.