Can anyone please explain what might've just happened?

Previously, I'd been trying to solve a problem charging my Latitude E6420 past a certain percentage (I still am).

In an attempt to fix this, I set BIOS settings to default as I'd read on the same forum that this should remedy the initial problem; except, I'd only stumbled upon another: "Your PC ran into a problem and needs to restart" loop.

After several different attempts to fix the latter, I'd managed to do just such by entering Advanced Option > Troubleshoot > Startup Settings > Safe Mode. The last two are the significant parts.

And, almost like magic, it starts back up normally.

I'm asking what I could've possibly done to have solved the latter problem as I don't understand how, in all the attempts I'd taken, that somehow fixed it. My concern is maybe it's a temporary fix, and thatcsooner or later it should resurface.

For reference, I'd undertaken the steps in the following video (03:20-04:22):

Link