Does it go to the green screen with a peripheral attached and powered, or is this if the HDMI ports are empty?

HDCP is High Def Copy Protection, and the error message can engage if the source box (usually cable/sat box) detects that it's not connected to a TV. If you have a cable/sat box connected to the HDMI, try to reset that by unplugging it, waiting a minute, and then plugging the unit back in. If it's a different device, it may mean that the ports aren't working.

There's not a firmware available for that model, so if the problem is with the TV (and it sounds like it could be, if the port itself is disabled or disabling itself), having the unit inspected and serviced by a technician would be the next step.