iPhone 4S Display black after I restart it

I fix my power button a weeks ago. After that, some times, my screen is like moving, vibrating. I decide to turn off/on my IPhone.

After that, the display is white with a color line. I open it to verify the connector display with the logic board. the connector is bluged well, but display this time still black. So I try many things:

1. check display connector.

2. clean connector with a control cleaner.

3. reset the iPhone from my ITunes and by pressing home and power button.

But nothing change, do you have some advice? thank you.

NB: the display is not totaly black, is flashing when I press power button.