A3 2006 starting issue in cold weather

Usually my Audi is parked in my garage where temperature is around 10C, no issue starting. But it happen three times that it stay outside at temperature -5c to -15c, the engine will not start and cannot open the door with remote keys.



Had to boost the car, no starting issue in warm temperature. Its seems a voltage relay is nt engaging in cold temperature.



Any one has an idea to solve the problem



Thanks