Lenovo ThinkPad T420 Does Not Charge When Powered On After CPU Upgrade

I upgraded the CPU on my Lenovo ThinkPad T420 from an Intel Core i5 2540M to an Intel Core i7 2760QM with doing a bios update before the hardware upgrade. After the upgrade, the laptop performs better in heavier tasks, but the laptop only charges when it is in sleep or other power off modes. The computer does power on without the battery when it is plugged in. Is there a specific step I had to take, or I did damage something in the process? Thanks.