Whoa, that's a scary prospect !
Maybe a failing ignition switch or something common to the battery and alternator.
I hope you've dropped it off to a good auto electrician and that it's not an intermittent problem because that'd shake my confidence in driving it.
All the best and please update the forum on the cause & solution.
Loving my DS4 DSport - 1.6 THP160, EAT6 speed auto, Blanc Nacre
"Most Beautiful Car of the Year, 2013"