[aiharkness]

So, the issue with the phone end button is still there... i.e. the button will turn the device off but not on?

You sure you haven't locked the keyboard prior to trying to use the button to power on the device?

I don't know exactly how the button works. I don't know how much of the function is hardware and how much is software. But one would think the other OS was wiped in the process of installing the older version, so one would think any software corruption would have been corrected. So, I still lean toward a fault with the button.