Many of us have been there. Big issue, lots of tracking it down, simple solution. In my case, my 2017 R started to go into limp mode more and more often, until it happened every drive. Code reader said throttle circuit calibration error. I replaced everything in the throttle chain, both on the pedal/electronic side as well as everything on the throttle body side. None of this worked. I finally traced the wiring diagrams to a plug under the dash. Wires were stressed and severely bent at this plug. Relieving this stress and cleaning the electrical contacts in the plug resolved the problem. No further codes/problem now since I tracked this down.

 

It was the cause of the non-start. Not sure what caused the smoke. But I changed the belts and with the intake reinstalled the car appears to be having no issues.