Why is my screen ALMOST white of the dead?

Hello tinkerers,

After having unmount/mount my iPhone to fix the power button, my screen became white (Commonly called White screen of the dead).

But it's different from the thousands of topics on the Internet which talk about this issue.

- The iPhone is working (I can do everything with it).

- The screen was totally white, but now it's becoming day after day less white and more visible => it means I can now see the applications etc, but with difficulty. here is a screenshot to show you that: LINK

- Funny thing: Everything is displayed in black and white! It means, if I go to Settings/General/Accessibility and I turn on the white on black mode... everything will now be displayed in color !

Of course I checked that all the connectors are well connected to the motherboard (particularly the LCD one) etc.

My only assumption: maybe the connection is not good enough and I should clean the LCD connector with alcohol.

To sum up: Nothing is broken, the LCD screen is working but we can barely use the iPhone because the screen is 90% white. (Please check out the picture I attached to understand what is happening)

Thank you !