We replaced the alternator and the battery is good. But now the car is dying. The battery light came on and the lights started flickering on and off then the locks went crazy. Now the car lost all power and died. Do you know what it can be?
Start by measuring the battery voltage with the engine off, then charge it at a slow rate for an hour and measure it again. Remeasure that voltage with the engine running. It must be between 13.75 and 14.75 volts. If it is low, measure the three voltages on the three wires on the alternator.