Shut Down After Boot Animation

Hey all,

I'm experiencing something rather strange with my Nexus 6P, and I was wondering if anyone had some insight on what might be happening or how to further diagnose the issue.

Earlier today, my phone died after the battery percent hit 0. Later I plugged in the phone and tried to boot. The phone made it to the end of the boot animation, but immediately after the animation finished, the device shut down.

I let the phone charge for about an hour and the same thing kept happening. Note that this phone does have the bootloader unlocked and does have TWRP installed. Luckily, TWRP boots without an issue, but wiping the cache did nothing.

Does anyone have an idea of what might be happening?
Is there anyway to debug the phone while it's booting to see what's causing the shutdown?

Thanks!