the power adapter might also stop working when your internal connector on your MBPro is damaged.
That's the magsafe board, or also called a DC-in board.
Your best tip is to try another power adapter that you know is working.
If your cord, or the adapter (the white box that is actually your power adapter) already looks "burnt", then that's likely why, and you would simply purchase a replacement power adapter. Be sure to check for damage inside that magsafe connector. Dirty, or burnt, or simply loose-missing bits inside that opening.