Iphone 13 Pro Max Display not Wokring

I bought the new iphone 13 Pro Max before a cople of weeks. Last week morning when I wake up and take my phone for day to day routine its shwoing the Display is not working. Its showing white colour only. I used the phone for only 20 days and on that time the phone is not fall down or have a physical damage. Suddely one day thi incident is happen. When I submitted the phone for further procedure they are saying that we cant be able to replace the phone we can only able to repair the display only.

So my question is that Why apple is not giving Guranty for this incident as my phone is only 20 days older.

Have a look at attached photo and kindly please help for that.