Some smoke, no fire

Boeing's mods to the 787 battery system are at least partially successful.  On 14 Jan, this year, A JAL 787 started to smoke while standing on the ramp.  A single cell in the eight cell main battery got in trouble, heated up, and vented.  The main part of the 787 mods was a fireproof metal battery box vented overboard.  That part worked fine, the overheated cell did not touch off the rest of the cells in the battery, the ovrheating/fire was contained inside the new battery box.  Not clear is the effects of such a failure in flight.  Depends upon the flight I suppose.  If the engines keep running, the engine driven alternators will supply plenty of juice.  If we have first a battery failure, and then total engine failure, will the batteries ( there are two of them) have enough juice to get the gear and flaps down,  power the radio, and keep the cockpit instrument lights alive?  And keep the fancy fly-by-wire system working? 
   Anyhow, doesn't look like they have licked the battery bursts into fire problem, but the battery box is strong enough to contain the fire.