Support galaxy s3 power button problems & others

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http://androidforums.com – Hello , stumble up in this website doing a google search glad I did..anyhow.. I bought a used galaxy s3 is 100% mint almost everything works perfect except sometimes the Power button wont work and when pressed the Shut down, restart dialog box pops up then after that the button dont work , I have to wait for the screen timer to sleep and hit the Home button then the power button works again for a few minutes. also the screen turns on by itself for a few minutes and when phone is off and I plug the charger the phone vibrates a few times and automaticly turns on by itself. I openend the phone (General)