So I picked up this used 2016 500e recently. Yesterday, on my way to the mall, the car's electrical system warning light came on. I tried restarting it a few times, but it wouldn't go away. I even disconnected the humidity sensor, but still no luck. Weirdly enough, I managed to drive it home for a bit. I checked the battery and it seemed fine. Thinking I could fix it, I went to disconnect the battery, but I accidentally disconnected the wrong thing. After waiting a bit and reconnecting everything, the car was completely dead. I tried everything, but it still wouldn't start. I'm getting pretty frustrated. What do you think could be wrong? Is it the battery?