Xarcell Doesn't matter how long it is held. I have held it until it rebooted twice. I just did it again for 60 seconds, and 1 minute and twelve seconds. No change.
Though it wouldn't make sense to rush to this conclusion, perhaps the power button is broken?
Three things to try:
- Hold down both the power button and the volume-down button together for 60 seconds
- Hold down both the power button and the volume-up button for 60 seconds
- Take the device to a repair shop and see if they can get it to turn off
Note that releasing the button for even a brief instant may cancel the countdown by the power controller.
Perhaps somebody else will chime in, but in my experience pressing the power button continuously for a minute has never failed to shut down a Pixel.
It is possible that power and volume-down, if held together for long enough, might restart into Fastboot, which would also be great.
But if you completely can't get it into Fastboot, taking it to an expert may be the thing to do.