The 'rubber' like material has micro fibers that transfer the electrical signals to the LCD.
This 'rubber' has little dark sports that are the fibers.
If it is not correctly installed then you get these problems.
Why did you have to take it apart?
Make sure that the area that the location where the 'rubber' goes is truly clean, use a soft tooth brush and LITELY clean the area and then when you install the 'rubber' make sure that the little dark sports are facing to both the board and the LCD.
Also the LCD only goes in one way.
Give that a try.