I had my catalytic converter replaced in October 2018. Since then, my car has started to switch off completely. It'll be completely dead - time off, odometer off etc. It will eventually switch on after a few minutes. It started in Dec and only happened once or twice. Now its happening more often. It even switched off while I was driving with my baby. While on the freeway this past weekend, the steering wheel locked and the car switched off. The one time it switched off for long, my boyfriend went to look by the battery. As soon as he touched by the battery, the car switched on. We're assuming the battery wasn't reconnected properly when the converter was replaced. Need assistance with checking this because it's very unsafe to drive with my baby and the car just decides to switch off.