- With the new alternator installed you'd want to verify if there's any sort of voltage drop when you go to start it. You'll use the voltage to check what you see when there is no cranking going and then what it drops too when someone else attempts to turn the vehicle on
Check Wiring and/or Voltage Regulator.
- Inspect wires to ensure if one might just be damaged and that may be why all this keeps occurring as well
