@Squirrel Indeed, actually the button is held by a c-clip like on a forerunner watch, that you can spot just from behind.
Thought it would release the middle cover from the front, but it did not.
A piece wants to separate when using a spudger, but somethings holding it, just from the buttons side.
Yep the crystal delaminated the glue is on me, trying to soften the glue introducing some drops of ipa alcohol, expecting the crystal to come up with heat, using a succion tool, but it did not