Unplug everything in back, except the power cable, and leave it so the device can cycle/reset itself. This may take several hours, FWIW.
My other thought is that it has something to do with HDMI/Anynet. Not sure if this is related to your actual device though. Try asking in the Samsung forums here for this info maybe....
I have had this home cinema for a little while now and it's not working properly. The light keeps flashing and when I press the power button to turn it on nothing happens and I get no display

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