Does your iPhone 6S/6S Plus  have very dim screen? You can see the picture but just barely. Or maybe half of your screen is dim.

If you have any of these issues that means you need backlight repair.

There are multiple reasons you have no backlight:

• Just your luck. Once one of multiple parts involved in the circuit fails. It does often create a domino effect. One part fails, few others follow.
• unplugging the LCD connector from the logic board while LCD is powered on.
• while replacing the screen with aftermarket assembly that has backlight connector exposed, shorting the circuit when closed.