Is the phone really not booting/powering on or is the LCD just damaged and not producing an image? Do you hear notification sounds from the phone even though there is no display? Let’s try a few things.
Connect the OnePlus 3 to a computer and power on the phone. Does the computer recognize the phone? If you had USB debugging enabled, you should be able to access the contents of the phone or use ADB to pull files off of it for data recovery purposes.
If the computer seems to recognize the phone, the LCD may be damaged so it no longer produces an image, making it seem like it isn’t booting/powering on. The drop damage could have potentially dislodged the battery connector as well, so that may be something to check for.
You can purchase the global version of the OnePlus 3 LCD from right here at iFixIt. I’d start there and also check the battery connector to make sure it’s connected.
OnePlus 3 Screen