Had this same issue few months ago, where i dropped my bag with iPad in it and the frame had the lightest bend, due to which the power button was unresponsive.
Took it to a local repair shop and he broke the display while trying to repair that but somehow got the power button working. Got a new display and alls well.
Now fast forward to today and my power button is suddenly not working again. Clicks but doesnt register a click. Anyone else faced this? And what was the resolution?