No, Elon Musk Did Not Die in a Car Battery Explosion
We are not exactly sure why people started to spread a death hoax about Musk. Some have speculated that it may have been an attempt to manipulate the stock market. One version of this hoax, for instance, was dressed up as an official announcement from Tesla.
https://www.snopes.com/fact-check/elon-musk-death-hoax/