Same problem, but just solved it! I didn't tether it properly. You have to hit the tehered boot button on the computer, then plug in the usb, wait for fast flashing, a few seconds and plug the power cord in also.... then you push the 2 buttons on the remote. When the program finnishes tethered boot you unplug the usb cable but leave in the power cord.... I just plugged in the hdmi and it worked.
When I first did it I only plugged in the usb cable! The instructions were actually very clear, I just misread it.