I would check the connection on the motherboard to the speaker that is illustrated in this video. https://youtu.be/VpVjaOBv6Lw

Check the cylinder for compression and the timing.

I have found that understanding the Difference between the Brightness and Backlight of your LCD is key to adjusting your television to the best preferred lighting. While the "Brightness - changes the colours of the pixels on the LCD screen. ... the Backlight - is the intensity of the fluorescent lamp behind the screen that makes the picture more intense. If you’re setting for brightness is set at the lowest level, check the level on the backlight to be at a minimal setting to reduce the intensity of the actual screen picture.