I was having battery problems so I installed a new battery in thee vehicle. I later realized that the alternator was the problem, so I replace the alternator. Upon starting the vehicle, everything worked fine aside from some rather loud squealing coming from the engine. Assuming it was the drivebelt, I tightened it, and now the engine refuses to even try to start. Battery is brand new and working fine, there are no warning lights on, but all electrical systems are working fine.