Please explain how a "charger" for a white dwarf might work! I mean, you could just chuck a huge ball of hydrogen at it; that might work, but it'd be easier to just bundle together two balls of hydrogen and make a new star.

I think I'd expect a charger to restore a phone to something like its as-new functionality. I've never heard of any mechanism that could change a white dwarf into not a white dwarf, other than extreme age, or being merged with another object.