How many software engineers do you need to change a smart light bulb?

None. It is a hardware problem.

It depends on the regional dialect:

Q: How many Northern Californian software engineers does it take to change a smart lightbulb?

A: Hella!

Q: How many Southern Californian software engineers does it take to change a smart lightbulb?

A: Totally!

https://escholarship.org/uc/item/6492j904

http://www.sonomastatestar.com/opinion/2014/11/4/hella-nor-c...

http://prizedwriting.ucdavis.edu/sites/prizedwriting.ucdavis...

https://en.wikipedia.org/wiki/Hella

One call center agent in India. He will SSH in remotely and reboot it for you.