My battery light has started to come on in my car when I start it. It then turns off after 20 seconds or so of running.

The little battery buzzer buzzes the whole time I am driving though. Also, all of my instruments (Save speedometer and clock) and most warning lights don't work. Also, when I open the door and the engine is running, the reminder buzzer goes off, like it doesn't even know that the car is running. Other than that the whole electrical system seems to be running normally.

I think this all started when my brake sensor light started to engage.

The fuses are all fine.

I'm sure these things are all on the same circuit somewhere, if someone could help me out in troubleshooting the problem I would be very grateful.