Xi6 set top box will not turn on

I replaced my old set top box with a Xi6 in October of last year. 
Ever since then, when I turn on the TV, all I get is a blank screen.  When I reset the box (unplug the power) I get the normal messages of "Welcome.. etc",  and then an unusual message something like "you caught us in the middle of a household update..."  and the screen goes blank again. 

I noticed that if I press the "Xfinity" button on my remote, I see the menu, but the screen is still blank. If I press Channel Up I get an error message "Please try again XRE 100007". When I try again to switch the channel, the TV works fine, until the next time it gets restarted (by myself, or during the nightly software update)

Later I also noticed that if I unplug the HDMI cable and plug it back in, the STB wakes up fine. 

Here is what I did to solve the problem so far:
1) I swapped the box with a new on from my local Comcast office.  DIDN'T HELP 
2) I replaced the HDMI cable with a new one (came with the box) DIDN'T HELP
3) I replaced the TV set to the latest model (yes!)  DIDN'T HELP

Somehow when the set top box gets restarted (or updated in the middle of the night)  it will not wake up when the TV is turned on.  un/plugging the HDMI does cause the STB to wake up 

I'm not sure what else I can do.