How is that Genie Client's video OUT connected to your TV? What cable/connection are you using?
Most likely that TV doesn't support the video resolution being output by Genie Client. The bootup screes are 480i SD resolution, then it switches to a different resolution based on the setting of the Client's HDTV/Video Setup menu.
I just encountered this issue yesterday. I have 3 clients, went around pressing the reset button to no avail. And only 2/3 turned on fine. This morning all weren't working! ugh!!! So I decided to do reset on my main receiver and for now they are all working. I'm hoping this lasts and is not going to happen often. I have only had Directv for last couple weeks. Hope this helps! On the genie hd/dvr, the reset button is behind a panel door you have to push on for it to pop open. Took only a couple mins for main receiver to reset and now all clients have a picture. Good luck!