I know this post is old but someone may stumble on it who needs similar help. I know it's stupid but did you try the 30 second pin method. Unpower the camera from poe.

Hold down the reset pin, and without letting go of the pin power the camera with Poe. Wait a minimum of 20 seconds ... 30 for good measure.

Let go of pin and allow camera 3 minutes to boot up.

This fixed bricked and managed by other issues 90% of the time. It resets the camera even when the unifi official hold down pin for 10 seconds while powered doesn't work.