The problem might simply be your screen brightness.
So if you can interact with Siri, try asking her to turn up the screen brightness to the maximum.
use siri to turn screen brightness up on iPhone
ask Siri to turn up your screen’s brightness for you!
See if that makes a difference. If not, keep reading!
Use your device and see if it performs normally.
Perform a hard restart
On an iPad with no Home Button and iPhones 8 or later: Press and quickly release the Volume Up button. Press and quickly release the Volume Down button. Then press and hold the Side/Top/Power button until the device restarts Forced Restart Not Working on iPhone 8 or iPhone X?
On an iPhone 7 or iPhone 7 Plus: Press and hold both the Side and Volume Down buttons for at least 10 seconds, until you see the Apple logo Forced Restart Not Working on iPhone 8 or iPhone X?
On an iPhone 6s and earlier, iPad with a Home Button, or iPod touch: Press and hold both the Home and the Top (or Side) buttons for at least 10 seconds, until you see the Apple logoiCloud keeps asking for password (iOS and OS X); fix
If you see the Apple logo, it’s unlikely the problem is hardware-related but rather was a software issue.
Use your device as you normally would and see if the problem resolved.
Check your temperature for blank or black screen problems
Black or blank screen problems often occur if you operate your device under extreme temperature conditions (like being too hot or too cold)
If too hot, just place your device in a cool area for several hours to let your device to cool down
And if too cold, put your iDevice in a warm area (but not hot) for several hours to allow it to warm up
Using an iOS device in frigid conditions outside of its operating range might temporarily shorten battery life and could cause the device to turn off
Battery life will return to normal when you bring the device back to higher ambient temperatures
Try and always use your iOS devices where the ambient temperature is between 0º and 35º C (32º to 95º F)