Following the Schwarzschild metric, we could consider that a white hole=black hole with no angular momentum (no spin?) or electric charge. Would be enough to slow down a black hole and somehow remove its electric charge to create a white hole?
To slow down and reduce the electric charge of a given black hole I can think of two methods, one by feeding the black hole other black holes with different charges and angular momentums or by creating a dyson-like object to slow the rotation little by little by using light beams and make it rebound near the event horizon. Which alternative seems more feasible?
I remember hearing that 'if' it was possible to turn a black hole into a white hole by somehow reversing entropy locally, it would implode back to a black hole as soon as you remove the energy source that is causing the "local entropy loss" (pretty sure I heard it on PBS youtube channel, I'm not sure if it's related to this paper studying the big bang as a fake white hole). Is this still up to date?