I tried several different methods that they suggest on the Google/Android support page. and it's been over 12 hours now and the phone still won't boot up. It gave me the recovery mode menu where it asks you what to do, but this menu looked completely different to me than I was used to, so I just pressed the power button, thinking it would reboot normally after that.
So I just let it charge for a while, then tried to boot it up by pressing both the power button and the volume down button. However, it never actually booted up after that, it only showed the Google logo for about 10 seconds and then the screen went black. She told me it wouldn't turn on, so I tried doing the old 'power button + volume up button' trick and it seemed to work. I haven't been able to boot up my mom's Nexus 5X since yesterday evening.
