Start-stop meteor

IT DOESN'T sound like an electrical problem, rather a problem with the carburettor, the auto choke in particular. I'm not sure what your mechanic did when he advanced it to open more quickly. But if the choke comes off too soon it will be too lean when you come to restart the car. When you turn off the engine after a short distance the auto choke will come off. But because the engine isn't fully warmed up it can need some choke to restart. With no choke it won't start. Have your mechanic check the choke to make sure it is set to specification and is working correctly.