This is the repair button i created for my mom's IQOS 2.4.

You have to carefully disassemble IQOS (there are videos on YouTube), remove old button (you have to cut off plastic but be sure not to cut metal inside the plastic).

Then you put metal part on the new button extruded back part and glue it with glue gun.

I printed with 0.4 nozzle, 0.42 layer width, 0.15 layer height, with supports and brim.
It is a little difficult to remove supports but I think they are necessary.