It could be your are using a resolution that doesn't work over hdmi or one that your display doesn't support. Try setting your project to 1280x720p, and retest. You can also update to the latest beta firmware.
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Aaron2
We have tried 1280x720p, and all other resolutions. Same issue.
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RokuLyndon
Ok, please submit a request to support @ brightsign.biz for an RMA. Please include your address and serial #>