Default [Q] hardware issue: broken power button on (mother?) board -->

hey there,

I have been having problems with my power button for quite some time and some weeks ago it totally stopped working. As my phone is rather old and worn I did not want to send it for a a repair shop (its out of warranty). I started disassembling it and realised that the power button came loose from the board behind the inner (blue/red) plastic cover located under the back case.

hence, if I apply the power button, it is not pressed, but its case moves down some milimeters.

my question is how to reconnect it to the board: glueing? soldering?

thanks in advance