I have an Audi A3 Ambition car and have bought it in August, 2017. The seller mentioned he built in a start button, so the car needs contact using the key first, then the motor starts by pressing a button (similar to this).
But after a while, issues with starting the motor began. At first the car didn't start sometimes in the first attempt. Another attempt of starting the motor was successful. Until the day, the car could not be turned on anymore. I brought the car to the service for repairment. They changed the starter which was obviously wrong. But there was a suspicion, that the real cause was custom electronics / electronics modification. The starter turned on again, after two weeks, on a trip to vacation. The suspicion is the electronics as the mechanic said.
The question is: what can cause an random activation of starter during drive so is getting destroyed?