Need to analyse the development process
The analysis of these problems needs to look at more than just the direct technical cause. Many processes must have failed or at least not worked well to get to this stage:
1. Specification - is the specifictaion of the components concerned adequate?
2. Risk/safety analysis - battery fires are obvious potential hazards what does the analysis say and what risk control measures are in place? The analysis should have included safety following failures or defects.
3. Verification - The ccomponents concerned and the risk control measures from 2. should all have been verified
4. Life and environmntal testing. The components concerned should have been tested at environmental extremes, shock, vibration and with accelerated aging.
Assuming this is another battery fire then it is suprising to me that they have happened so short into life and so relatively frequently. Safety issues for systems desigend and developed using a safety process are usually complex, multi-faceted involving multiple causes or involve obscure and difficult to predict failure mechanisms. At the moment this does not seem the case. Understanding why this got through the development process is key because if the prcoess is suspect many more areas will need to be looked at.