Here are some high-res pictures of the power button:
Back: There are 3 contacts. 2 for trigger, 1 for securing it to the PCB?
Underneath: not much here. Those two big contacts are way too far apart to be the trigger:
I know the contacts look pretty big in these pictures, but here it is, a bit zoomed out. It's that tiny black element in the top right corner, next to the LEDs:
Any advice? I think I can see the tiny metal thing that's holding the button housing together, but it'd be nicer not to destroy the button permanently.