One possible solution you can try is to update the BIOS firmware of your laptop. Sometimes, outdated BIOS versions can cause power-related issues. You can download the latest BIOS version from the Dell support website and follow the instructions on how to install it on your laptop.

If updating the BIOS does not resolve the issue, it may be necessary to bring your laptop to a Dell service center to have it checked by a technician. They can diagnose the issue and provide a solution based on the specific problem with your laptop.

In the meantime, you can also try using a different AC power adapter to see if it works with your laptop. This can help determine if the problem is with the adapter or the laptop itself.

This forum thread may help. Considering that you replaced those parts (Genuine Dell OEM I hope), then the next step would be to replace the DC jack on the laptop. If that does not help then the only other possibility is a bad MB.

EDIT: @JudithCrabb is also spot on and types faster than I do.