Have you tried pressing the "STB" button, then the power button, on the remote?
I've found the remotes that came with our 7200 series boxes to be less than intuitive in that regard. But I've never had a problem turning the STB on using that method, or using our Harmony 880 universal remote.
Yes, I made sure I pressed the STB button and made sure that it lit up when I pressed the power button.
