XPS 12 9Q33 Black Screen on startup

Hi,

After working perfectly for the last 4 years, my XPS 12 suddenly stopped working recently. I'll give the most thorough explanation of what happens, after which I'll summarize what I already tried to fix it.

First, it started randomly crashing now and then, not at a certain specific time. If audio was playing, it got stuck and the screen froze and displayed red pixels in between what was playing at that moment.  A restart using the power button usually did the trick.

The last time this happened a few times in a row (upon entering my credentials, it froze again in the same way) and now it won't start up anymore. The power button is glowing, the backlight is on, but the screen stays black (the fan stops spinning after a few seconds). It's not just the screen, as when I hold "D" on restart, it correctly displays all the colours, and I can't enable/disable backlighting,...

I opened it up, unplugged the battery and CMOS battery and tried restarting, this didn't work. Holding the power button down for 30+ sec also doesn't seem to do anything. Pressing "del" or "F12" on restart doesn't seem to do anything either. Taking out the SSD doesn't have an effect, which leads me to believe this is not a hard drive failure. Finally, I also tried flashing the bios using the bios update tool and a USB, but this USB doesn't seem to get power when plugged in (light stays out). I really can't seem to make much sense of it, except that maybe this all points to a motherboard failure.

Thank you so much in advance!
If any more information is needed, I'll be happy to provide it!