Ok,here's a new theory.
Maybe she was sitting in the tub,enjoying the companionship of her "portable battery-powered personal device that also plugs into a 110 volt wall circuit",decided she needed a little more action,and somehow plugged it into a 220 volt wall circuit? Couldn't THAT have possibly caused her to throw a arm out to "Praise Jesus" with enough vigor that it damaged both her hand and the tub?
For your own mental and emotional safety,please do NOT try to develop a mind picture of this happening.