Lenovo — Display failure in Laptop and poor quality and service

I own a Lenovo laptop which is 1+ year old and the laptop was functioning fine before 2 weeks. I rarely use my laptop and I got extended warranty for it. But suddenly before 2 weeks when I turned ON my laptop, the display is flickering and totally not working. When I approached the service center, they told me that the screen is damaged internally even though there is no external physical damage in the display glass and they said it will not be covered under warranty.

If a display can get damaged even there is no damage on the external glass, what a low quality display is being provided to the customers by Lenovo.

I want Lenovo to replace my display with a good one under warranty.

If any other details required please let me know.