So recently after replacing the original battery with a varta silver dynamic a few days ago, the car shut off on me whilst I was driving. Once I try to start it again completely nothing no click no crank or anything. I managed to get the car home by jump starting it a few times and leaving it to charge for 10 mins, luckily I wasn’t too far away. What could this be? I assume either starter motor or alternator. Car has only 85k miles on it. It started up yesterday but still displaying red battery light 

With the car running and the battery light on, check the voltage at the battery and see what you get. Sounds like the alternator though.