So apparently the employees at google weren't able to detect any display issues. All they offered was replacing the screen due to a tiny hairline crack in a corner.
They also decided that the replacement would cost 140€. I can buy the same exact phone on Amazon for 339€. Even just purchasing a replacement screen costs roughly 100€. (Even if it weren't that expensive, I have a feeling that I shouldn't attempt a DIY since the insides are probably a complete mess.)
I'm guessing the screen is currently blacked out to the point that they assume it just doesn't turn on. There isn't even any place I can leave a comment or question. Only an accept or decline button. They almost certainly didn't open the phone as it would be a slight hassle for them.
(The phone's screen was already 80% blacked out by the third day. They just responded on the tenth day.)
The phone is just half a year old...