I doubt we will ever hear the details, it's so tragic that I think once an investigation is done, it will be kept to the family.
Here's my scenario: "in the bathtub" implies she was likely lying down in it, head propped up on one end, phone at her ear. The phone started to die, she reacted by grabbing the charger with wet hands and plugged it in, after making the charger and cord wet all the way up. Electricity tracked along the water to her hand, across her heart to the plumbing. The burn mark was from that tracking, not from the phone case itself, that was conjecture. Now, why was there a receptacle within reach of the bathtub that was not on a GFCI? Old installation that was never brought up to code. My parent's house built in 1951 was like that; you could be in the tub and have a radio fall in and kill you. That's WHY they made it code to have GFCIs in bathrooms.
Heard an interesting discussion on the radio about brain development in teenagers. They have thousands of times more neural connections than adults over age 25 do, so that's why they can think faster and believe they know more; they are absorbing high volumes of information very fast and it makes them think they are super human. But until the age of about 20, almost none of those neural connections are making it to the prefrontal cortex, the area of the brain where logic and reasoning take place; the "if A then likely B or C" is thought through. the neural connections start at the back with basic animal functionality and work their way forward as we age. After 25, all of the connections to that prefrontal cortex are complete, and our brains begin "trimming the tree" of all of these relatively useless neural connections, optimizing our brain function by using logic and reasoning. That's why Teens need adult guidance; they need our prefrontal cortexes until they can make rational decisions on their own. Like not plugging a phone charger into the wall while in a bathtub...
