Use the following cheats while in pause:
Unlock Infinite health: 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.
Unlock Infinite ammunition: 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.
Unlock 500 Thermal Energy points: Up(2), Down(2), Left, Right, Left, Right, X, Y, RB + LB.
Control intermission sequence: B, A, X, Y, B, A, X, Y, B, A, X, Y.