reviving completely dead battery is undocumented
At https://docs.puri.sm/Librem_5/Troubleshooting.html#recharging-procedure is covered how to revive a battery that still has enough juice to show some immediate life signs in the corner LED.
My dogwood phone is currently dead and I am told to try tricks that involves a) using a USB A to USB C cable, b) removing the battery, and c) charging for hours before expecting a life sign in LED - all of which are dofferent from the documented procedure.
I think it would be relevant to document these more complex trick as well. Perhaps discouraged by putting it in the developers' documentation and only link to it from the user guide, with a slight warning?