Now this techie friend's version is:
The virus gets into the system......the operating system has to be a higher version. Symbian or higher.
It starts disrupting the battery - electronic circuit board interface.
Let me give you an analogy related to your computer:
SMPS regulates voltage to the PC motherboard by turning on & off the power transistors. A boot sector virus can mess up the BIOS so that the power transistors go totally awry.
Result : KA-BOOM
Thing's a bit like that.
When you put to charge your battery...the virus gets ACTIVE. Then if you answer a call while it's charging..........
The virus plays haywire with the charge being distributed.......
Researchers are still trying to find out the exact mechanism.