Ever since I got my last Q box (a replacement for the original faulty one), I periodically had the same issue you have described.
Usually, unplugging it, then plugging back in, and going through the Welcome screen fixed it. A minor pain, but it worked.
More recently, that didn't work anymore, and I had to do the reset (holding the reset button whilst powering on. That worked three times over four days, but I called Sky on the third time (knowing there was a real problem) and they immediately sent out a new box. That arrived on the fifth day (less than two days after it was ordered), by which time the reset didn't work on the old box one last time.
You've got to call Sky.
FM
