It sounds like you've already taken some steps to diagnose and address the battery-related issues with your Challenger. Since you've replaced the battery and are still experiencing issues, there could be a few other possibilities to consider:
Battery Connection Issues: Even with a new battery, poor connections can cause problems. Make sure that the battery terminals are clean, tightly secured, and free from corrosion. Loose or corroded connections can prevent proper power distribution and starting.
Electrical System Issues: Modern vehicles have complex electrical systems that control various functions, including starting. There could be an issue with a component within the starting circuit, such as a faulty starter motor, ignition switch, or related wiring.
Key Fob or Immobilizer Problems: The issue you mentioned about not being able to unlock the door with the key fob could be related to a key fob or immobilizer problem. If the car's immobilizer system isn't recognizing the key fob, it might prevent the car from starting.
Computer System Glitch: Sometimes, electronic systems in vehicles can experience glitches or errors that affect normal operation. This could potentially cause issues with starting and other functions.
New Battery Not Charged: While you've replaced the battery, it's possible that the new battery might not be fully charged when you installed it. Batteries are typically shipped with a partial charge, and it's important to ensure that the new battery is properly charged before expecting it to provide sufficient power for starting. If you didn't charge the new battery before installation, it might still have a low charge, which could contribute to the issues you're experiencing. Try charging the new battery using a battery charger. If the battery charge was the main issue, this might resolve the starting problem. Or use a multimeter to test the battery voltage.
