No. um, maybe. er, um... whoa.....
So does a stretched rubber band weigh more than an unstretched one?
Potential energy /= mass, I thought. A bucket of water at the top of a mountain is the same mass as at the bottom, but has potential energy, right?
BUT a stretched rubber band is storing energy in Van Der Waals forces & latent heat, so E=mc^2 yes, that increases the mass, right? just by not a measurable amount.
So... a battery - they are like a rubber band, potential energy using a chemical-electric energy gradient. Electrons really want to get from - to +, but the overall number of electrons doesn't change. ie. the Battery (or cell) DOESN'T have an overall 'charge' in the classical physics sense. Am I right?
Ok, um, I choose NO - the Kindle does not weigh more, as that would imply direct mass -> energy -> mass conversion, and stuff like that ALWAYS kicks out a few alphas, betas, gammas and probably a plethora of neutrinos.