OK. Well, we are a long ways from agreement on that one. Where did you see "Go" for that unit? Really no matter, though. The "WN" should tell us all that we need to know.
What I show for "WN" serials is called the 'Start 60' in the UK. Here in the US, we call it the Via 1605. It has one of my favorite 'resistive' screens ever. Very bright and sharp for that kind of design.
If I've got that all correct, the good news is that I have one right here to work with (another "WN" device). Does your unit have the power button high on the rear, not far to the right of where the mount ball connects to the device? Is there also a small flip open door in the bottom center of the unit? You'll have to look closely for the seam line and pry down and out from the back side with a fingernail to open it. It's a nice fit. The actual model number should be on a label under that door.
Perhaps we can work together to get your button working again.
Please confirm the description of your power button location and the presence of the door at the bottom (and perhaps the name on the label), and we'll get to work.
First, a question about the 'feel' of your button as it is now: Only one side of the button (the side with the universal power symbol) can be pressed to cause the switch inside to operate. When you press on that symbol on the button, it should detent slightly (about a millimeter or so), and return to its unpressed position easily. There's definitely tactile feedback to be had there. Before we pull the case apart, how does it look/feel to you when you try to operate it?