Power button is extra broken for me...

Recently my Samsung Galaxy Ace 2 I8160 power button went completely coucou. I don't really think it's only broken, it can't make a screenshot when I press home button and power button at the same time. All it does at this part is to go to the home screen.

Also I can't 'lock' the phone. When I press the power button to lock the phone, it doesn't lock. And most of the time when I try to either use power button or wait until screen times out a couple of times, the device immediately restarts itself.

What happened here? Is there a way I am able to fix this?