Update on my broken HUD

I have a 2023 Chevy Suburban Premier and the HUD kept going out completely, flashing, or a combo of both.

Took the vehicle to the dealership under warranty and they tried to install two different brand new HUDs in my vehicle and it’s still not working. It’s now sitting at the dealership to be worked on by a GM engineer. They mentioned that GM engineer had to do the troubleshooting since it’s under warranty and the documentation would be needed to either reimburse the dealership for the work, or to pay us out if they can’t fix it. Is that really a possibility that it’s not fixable?