Beware Hot Alternator

This '07 Lexus Is250 stranded my customer on a busy bridge during rush hour with no warning.  No warning lights came on. She rolled to the shoulder with no power, windows would not go down, emergency flashers would not work. Something caused the relatively new battery to drain instantly while driving. Car was towed in with a terrible burnt electrical fire smell. I charged the battery and when I hooked it up a welding arc burned the lead terminal and the burnt electrical smell got stronger.  It seems like the alternator shorted out internally, possibly the electric steering did too . We find out soon.