Need help with starting my car

To avoid killing your starter just because the Blynk MCU locks up… perhaps separate your starter relay and RPM sensor into its own non-Blynk code on dedicated MCU that can than interface with the Blynk MCU as needed (via i2c or even serial perhaps?) EG. to start when asked, sense results, abort/retry as needed and confirm success back to Blynk MCU when finished.