Can't boot normally after shutdown

[DethDonald]

I'm moving my question here because my hardware issue have been resolved and all I'm left with is what i believe to be a software problem.

Occasionally after a shutdown my FreePlay Zero wont boot normally with the power switch. Re-writing the image to the SD card fixes it momentarily as does plugging a USB cable into the Pi itself or unplugging the battery and moving it to the second slot. I'm using the 2000 mAh battery that I purchased a long side with the Zero kit if that makes any difference.

Is there some code somewhere telling it to boot off the alternative power slot?

[Flavor]

No, the Pi itself has no "idea" which pin the power is coming from, as far as I know. I'm wondering if there's any chance that there is a poor solder connection on the Pi that's causing an intermittent connection or a bridged pin that is conflicting.

When this happens, what does the FPZ look like when you hold the power button? Does the LCD light up? Does the green LED ever come on?

Would it be possible to take a video of this condition? Maybe we'd see something abnormal that you might not notice, because you don't have other systems to compare to.

[DethDonald]

If its in its non-booting mood nothing lights up. Once I switch ports the screen will flash when I insert the cable, the screen will light up white while I hold the power until the green light turns on and the Pi boots.

I'll work on getting you a video.

[Flavor]

If you disconnect the batteries entirely and just use the MicroUSB port on the Freeplay Zero board, how does it act?

Can you show a photo of the Pi Zero pin header solder? This is normally the root area of most FPZ issues.

And, a vid would still be nice, I think.