Z3 compact the yellow button

[Umutq]

Hi guys today I see the yellow button on the sim card slot somebody explain what does it do?

[Qatrium]

It's use to force shut down your phone if it's totally unresponsive.

More information on Z3 Compact user guide (page 143-144):

http://www-support-downloads.sonymobile.com/d5803/userguide_EN_D5803-D5833_4_Android5.1.pdf