Nexus 6P stuck between google logo and error screen

[Android Central Question]

I've had my Nexus 6P for a little over a year now, and in that time I've had no problems. Starting today, the phone won't boot and is stuck alternating between the "google" screen (with an unlocked padlock icon) and an error screen telling me my system cannot be checked for corruption and I need to lock the bootloader. I've tried using recovery mode but it sends me back into the loop.

Any help is greatly appreciated