Edvic,
There is no "cable on/off" switch, at least not as far as I'm aware. I imagine that what you have found is the antenna amp switch. On our Axis it is located in the small, top cabinet over the sink. It's way in the back and really hard to see/reach. It must be OFF for cable, ON for over-the air.
If you've only found 9 loose screws you are doing well. I've found a hundred or more as I explore all of the various nooks and crannies. I'm thinking of opening a hardware store...
Randy