Press START during gameplay.

Input YELLOW, BLUE, BLUE, BLUE, YELLOW to add two more power nodes to your inventory.

Input YELLOW, BLUE, YELLOW, BLUE, BLUE, YELLOW, BLUE, BLUE, YELLOW, BLUE, BLUE, YELLOW to add five power more nodes to your inventory.

You can only use the above inputs once per game (you do it again on a New Game Plus).