Hi there--I made the mistake of letting my phone drop to 0% charge, and have entered boot-loop hell.
While plugged into power: I reach the "your device is loading a different operating system" screen, I press the power button to pause the loading (per previous discussion threads on this topic), and I waited 5-6 hours for the phone to charge. After all that time, the phone has only regained 87% battery and appears to be stuck at 87%, despite leaving it plugged in for more time. When I un-pause the booting, GrapheneOS loads and I can see my normal lock-screen for a few seconds before the loop begins again. The lock-screen contains a notification that says "system server crashed" or something to that effect (if I click the notification, the loop begins again).
In the past, I was able to use the pause-during-booting and wait-to-charge method and was able to get back into my phone around 70% charge, but this time it doesn't look like that is working. Any other suggestions for things to try?