GraphiteOS I had the same issue, phone was working, but the screen went black. In my case, this is what happened in case it's useful to someone else:
The phone autoupdated to 2025050300 and needed to reboot, however, the battery ran out before I could reboot. Plugging it to the power brick I could see the grapheneOS logo so I didn't worry and came back later. However, I was presented with a black screen and apparently to feedback from the phone (note that it was on DND night mode, so no vibration was expected).
I tried force-rebooting with a combination of power+volume up/down, but as soon as I was presented with the SIM pin, the screen faded to black before I could unlock it (no matter how fast I was), this happened at least 3 times.
What solved for me was to temporarily remove my sim, force-reboot the phone, unlock it, wait until it charged completely. I left it like that overnight (I wanted to sleep), and in the morning I plugged the sim back and was able to unlock that too. I also tried rebooting the device with the sim inside, and everything is working perfectly now.
If it's an upstream bug, it is really annoying, scared the hell out of me.