Went to go run some errands today and my 2008 Mustang wouldn’t start. Didn’t even sound like the engine was trying to turn over. Lights flashed inside and CD player went absolutely ballistic. The dash said “check charging system” but only for a second before the car shut off again. We’ve been getting some pretty heavy rain and about two days ago, my passenger side floor was completely filled with water. I checked the cowel drain which was empty and changed my air filter. I’m not sure if the two are related. What’s causing this to happen?