Visible physical casing damage is probably not covered under warranty especially the screen. You can check your warranty card for details but I wouldn't put much hope into it unless you've phone insurance covering the device.

How extensive is the damage? Sounds like it's banged up pretty bad and if it's not turning on, either the battery connector is loose, motherboard damaged, power connector broken, etc. Considering the height (2nd floor), I think the motherboard might have suffered some major damage. Changing this won't be cheap as those Qualcomm chipsets do cost ~RM500-800 to replace.

Your best bet is to go to any SE warranty center and ask them to quote you the price to repair. Most likely it'll cost a bomb so you may as well purchase a new device if it's going to cost you over RM800.