It was not a thunderstorm it was a convective system, there was not any reported lightning by a satellite and sensors that monitors the presence of lightning. Read the first BEA report, again. Read Tim Vasquez's update, again.
Hint: From Tim:
* Lightning -- Though in earlier versions of this study I had identified lightning as occurring in this mesoscale convective system, recent evidence from spaceborne and sferic sensors indicate that this system contained little or no lightning. Soundings do indicate moderate levels of instability, but there are indications in the literature that cumulonimbus clouds in oceanic equatorial regions entrain considerable quantities of drier, cooler air that dampen upward vertical motion in the lower portions of the storm, and in some way this reduces charge separation 2. In any case it does look fairly likely that we can rule out a lightning strike as being a factor in the A330 crash. That said, it should be emphasized that lightning is modulated by distribution of ice and water fields within a cloud and is influenced by updraft strength, and is not simply a function of the storm's severity or predisposition for turbulence. Whether the aircraft was struck is the main item of concern, and it appears no such event occurred.