Q50 car help pls

So I recently ran into a key system error on my 2017 Infiniti Q50 (awd automatic V6), I was able to get it to start by turning the car on then pressing the brake and starting it (with a jump). I drove around for 20mins then parked and shut off the car, but noticed the engine was still running. Replaced the car battery, noticed a quiet whirring/humming as soon as I connected both terminals. Idk if this is related or just a normal thing.
When I tried starting the car again, I had to power on then press the brake and start. I could hear the starter would keep spinning but the engine wouldn’t start. Just ignition but no engine. This was the same thing when i initially got the key system error. I had went on a 400mi roadtrip just beforehand with no problem, but a few hours later I ran into all of this.
Im gonna try to odb2 scan it, idk what the problem is. Starter???