Enable Cheat Mode:
While playing, at the inventory screen, press L + R + Left Analog-stick + Right Analog-stick. Then, press the following buttons:

Refill health bar:
Up, Down, Left, Right, Left, Right, A, B.

Refill armor:
A, Y, B, X, Y, A, L, R.

Maximize rifle damage:
Left Analog-stick, Left Analog-stick, X, Y, B, A, Right Analog-stick, Right Analog-stick.

Maximize pulse rifle damage:
B, Down, Left, A, White, Black, X, Y

Maximize shotgun damage:
A, A, Left Analog-stick, Analog-stick, press Up, Down, Left, Right.

Maximize repeater rifle damage:
Left, Y, Right, A, Up, X, Down, B.

Maximize assault rifle damage:
Left, B, Right, X, Down, Y, Up, A.

Maximize bolt thrower damage:
X, Y, B, White, B, Y, X, Black.

Baby Nick Conner:
B, A, B, Y, Down, Down.

View credits:
X, B, A, Up, Down, Y.

Breaking Benjamin music video:
Left, B, A, L, R, Up.