Enter the following codes during Single Player Campaign mode to unlock the corresponding effect. To enter the codes just pause the game and enter them. These codes will only work on Easy mode and the current level that you are on and must be entered again after each level to activate them. If the code has been entered correctly you will hear a sound as confirmation.
Unlock Infinite Ammunition:
Enter: RT, RB, Y, X, Right, Down, Left, LB, LT, RT, RB, Y, X, Right, Down, Left, LB, LT, RT, LT, LB, RB, Y, Left, Down, X, RB + LB.
Down(3), Up, Y, Up, Y, Up, Y, Up(3), Down, X, Down, X, Down, X, Left, Y, Right, X, Left, Y, Right, X, RB + LB (Heat will still go down).
Unlock 500 Thermal Energy:
Enter Up(2), Down(2), Left, Right, Left, Right, X, Y, RB + LB.