Why battery just all of a sudden go dead
2 Answers
If battery is down, use a charger and get it charged up. Make battery cables/connections all good. Check your charging system. If battery isn't charged, we're just spinning our wheels. If battery voltage lost, it may effect your security system? If starter motor won't crank the engine, you may be able to jump switch side of starter relay, for testing, just to see if starter motor will crank the engine. If you try that, make sure transmission is in park or neutral and parking brake is set. Vehicle can't move.
Bad alternator, bad battery or dirty battery cables will cause that.