Maxbhi Elcotek Telecom www maxbhi com - Defective item

I have initiated my order for xiaomi lcd with touchscreen for redmi note ** pro max from maxbhi on *st July **** as they promised to deliver it by *rd July if I confirm it within * hour..and I did the same but they didn't deliver it as promised and I received it after visiting personally to courier service centre yesterday on **th July and as I tried to install it on my phone it's touch screen is not working and I complaint it to maxbhi at the same time ...what they replying after few hours is that your replacement request is declined as you have opened the item...How a person can check the product without opening it...??? They said everything should be intact it's cover it's stamps it's seal everything ..product should be same as they have send it...I have send them photos of the product it's cover it's stamps everything is intact but still they reject my replacement and looted me..what can stamps, seal do when the product is Defective.. And how a man can check the product without installing it.....so sad...