IPhone 6s screen cracked - unresponsive/hypersensitive

Dad got me an iPhone6s 2 weeks ago which fell and cracked yesterday. I noticed after an hour or two that the home button was a bit chipped off and a line went through middle but later on it went to the top - don't know how. Since then, it's been unresponsive/hypersensitive.

I just can't enter the passcode and get access. I pulled the screen protector off (yes, I'm surprised that nothing happened to the screen protector but the screen got damaged and my phone fell on its back not screen).

So yeah I pulled the screen protector off to see if it works - well for a bit it did but after a bit became unresponsive again. Does anyone have any idea how long it would take to sort this problem out? Maybe a few hours/days? And what would the cost be?

I'm really frustrated too that my phone earlier which was an iPhone5 got badly damaged - the cracks were far more worse yet it works perfectly fgs.

Is it still under warranty - does that cover accidental damage - if not adopt best apologetic face and ask Dads help to replace it.