For info Apache, something that I have experienced in the past was the 5000T switching on as a result of remote button presses for a box which had no CEC as it didn’t even use HDMI (an old Topfield TF5800 PVR which I no longer use). I never got to the bottom of that and could not even associate it with any particular button.
I am not saying that Graham is wrong as, in this instance, the CEC may well be the cause.
My 5000T often comes on by itself when I turn the TV on (or another Humax, or in fact press a key on any other remote). The TV doesn’t use CEC and I’ve turned it off on the 5000T in any case. I can’t get to the bottom of it either.