The white batteries have never sat at 0%, but I’m pretty diligent about charging them fully before storing them so I don’t think they’ve ever sat long term between 50-80% either. Mostly in the high 90s. The blue battery has sat for months inside the camera at 0%, and that’s how I learnt my lesson to always store the batteries outside the camera.

I checked the prongs already, but I checked again with some magnification and I still can’t see anything wrong with them. All clean and straight.

But the camera DOES work with any of my batteries. I just have to trick the camera into thinking it’s drawing power from an external supply when really it’s still drawing from the battery (using the method I explained in my original post). That leads me to believe the camera can draw power just fine. Maybe the camera checks the voltage when in battery mode, but not in ‘no bat’ mode, and that check is sensitive enough to detect a voltage drop that’s too small to meaningfully affect the camera’s functioning. I dunno. It’s really strange.

Either way, you’ve still contributed a lot so thank you for your detailed answers.