Iphone XR with black screen still after system update and factory setting restore

I've tried the volume up, volume down, siri button to restart - and I have never seen the white apple icon. I attached to my mac with power cable and tried both the software update and then factory setting restore. My screen is still always black. I know the phone is on and I know it's working, the screen is just nothing but black. I have not exposed it to moisture, shock, etc. Thanks for helping.