My Xperia Z2 can't reboot

[Lurc_Blight]

Hii guys i want to ask all of you about my problem with Xperia Z2.

After I updated the firmware for Xperia Z2 then I cant reboot my Z2 with power button.

Then how can I reboot without power off from power button ? 

[Mxillia]

Thank you so much, this worked like a dream after frustration I had.