Since the recent update was released into the wild a number of users have reported (and our own first hand experience) that the Xbox One will sometimes boot up with sound but not picture. This is highly annoying but can be remedied by resetting the console. To do this, simply hold the power button for 10 seconds, release, then wait a few minutes before switching back on (pulling the plug out the back is optional).
What we’ve found is that this hard reset of the console works, but doesn’t fully solve the problem as the blank screen might appear again – so you’ll have to repeat the process. We’ll assume Microsoft are well aware of the issue and will hopefully offer a more permanent solution via another update.