New install doorbell camera smoked and smelled burned - now working

I self installed my whole Simplisafe system with very few problems,  I installed the doorbell camera on existing wired doorbell power, measured 17 Volts,  transformer says 16VAC 30 VA.

The doorbell camera initially let out a puff of electrical smelling smoke in the area of the large button.  I figured it was fried, but a few minutes later, it is working fine?  

Any thoughts on this smoke and burned smell? I'm not crazy, I'm positive it smoked and smelled burned.