I've fixed this. For awhile, The solution for me was to slap the button side of the phone against my palm. Eventually, That didn't even work.
So I used eyeglass repair screwdriver and opened up the phone. There'll be a tiny slit of material that needs to fit between the plastic button and the sensor. Why button was stuck was because it shifted and got stuck.
So just gingerly lign it back up with the button and be sure not todislodge theguts of the phone and waterproofing seals.
When I got done I had a couple extra screws. LOL My phone has been working long after that so I guess I didn't need them. :)