Welcome to Cadillac Forums @VBXT4
Sounds like you need to take your vehicle to a more attentive dealership.

 

Run - don't walk - to another dealer! (If you are under 48K miles you should be covered!)

 

I mentioned this to a tech at Hendrick Cadillac in Norfolk and he responded with a shrug: "My truck does it too".

He should go back to tech school.

Google:

A black screen on a 2023 Cadillac XT4 often points to a software issue, a problem with the HMI (Human-Machine Interface) module, or a weak battery; troubleshooting steps include rebooting the infotainment system by holding the "END CALL" button, checking and replacing relevant fuses, and confirming the battery is adequately charged. If these steps don't work, a software update from a Cadillac dealer or replacement of the HMI module may be required.

Troubleshooting Steps

1. Reboot the Infotainment System:
   • Ensure your vehicle is in PARK.
     
     
   • Press and hold the END CALL button on your steering wheel for about 20 seconds until the center display turns off.
     
     
   • After a few seconds, the welcome screen should appear, and the system will reboot.
     
     
   • If your XT4 does not have Google built-in, you may need to perform a "door open" reset: turn the car off, open the door, wait for the dash to go blank, then close the door and start the vehicle again.
2. Check Fuses:
   • Consult your owner's manual for fuse diagrams to locate the radio and display fuses.
     
     
   • Remove and reinsert these fuses to reset the components.
3. Inspect the Battery:
   • A weak or dead battery can cause electrical system malfunctions, including a black screen.
     
     
   • Perform a charging system test on the vehicle to ensure the alternator is charging properly and the battery holds a proper charge.

 

A relevant thread:

https://www.cadillacforums.com/threads/xt4-electrical-issues.1139720/