One day and because the monitor button is to my right I must have pressed it in at a slight angle. The button slipped around and the next day I could not switch it on. Because it is smooth I had to use something sharp to carefully drag it back into place.
Apparently Dell made a wacky design decision with this model. You would expect the area under the button to be a membrane that was central and large in comparison to the button. Not here. The actual membrane is small and off center. The part of the actual plastic button that depresses that membrane is also small and off center. So because I did not use direct pressure at the right angle it slipped – and has done ever since.
The button cannot be removed. The button cannot be glued into place. I could have fitted an inline switch but that’s just hassle which should not be needed. It annoys when it needs dragging back but it does not otherwise harm the monitor except aesthetically. But given that the complaints in the Dell forums have gone back well over 2 years, and that the cost to change the design must be fractional it is strange that Dell continue to produce this inherently flawed model.