You can always try sideloading the update to fix any glitches that occurred while it was downloading.
First back up the phone (see
Backing up an Android Device) (just in case something goes wrong).
Go to
Google | Full OTA Images for Nexus and Pixel Devices, scroll down to marlin for the Pixel XL or sailfish for the Pixel. Follow the instructions at the top.
If that doesn't fix it, flash a new image to the phone. Download the factory version image for June from
Google | Factory Images for Nexus and Pixel Devices. (Scroll down to marlin for the Pixel XL or sailfish for the Pixel. The last file in the group is the June image.
You'll have to unlock the bootloader (see
Unlocking Pixel Bootloader). (Don't worry about the warning message you get every time you start the phone, it will disappear after you relock the bootloader.)
Unzip the file. Make sure you have the driver installed in your PC if you're running Windows (you don't need drivers for Mac or Linux) (
Android Developers | Install OEM USB drivers).
Edit the flash-all.bat file if you're in Windows or the flash-all.sh file if you're in a Mac or Linux computer in a text editor, find the line starting "fastboot -w update" and delete the -w part. That will flash the image, but not do anything to your files. If the phone still doesn't work, you'll have to put the -w back, run flash-all again. That does the same thing as before, but wipes all userdata (which is why you need the backup). Then relock the bootloader. Then restore your entire backup.