syseng68k, I'd stick with the LiON batteries for the short term (excuse that 'short' remark
). If it can be determined that these failures are related to battery age, number of load cycles or some other condition, an accelerated maintenance and replacement program can get the dodgy batteries out of the planes before they become a risk. That would be cheaper than keeping the fleet parked. And Boeing may have to pick up the tab (no cost to operators).
In the long term, a battery/charger/smart load controller may have to be developed and certified. This will be done with far more outside scrutiny by independent experts.