The Ryobi compound miter allows you two types of cutting freedom: the angle of the saw blade and the angle of the workpiece (with respect to the base of the saw). To make the tool easier to transport, the saw arm can be pushed down and locked into a closed position. At the job site the tool can be unlocked simply by pressing down on the saw arm and pulling out the lock pin.
Grasp the lock pin, which is the small, cylindrical button on the right side of the saw arm, just above the main pivot joint.
Press down gently on the top of the saw arm so the pivot joint floats freely between the upper and lower limits of its locked position.
Pull the lock pin out to the right, away from the saw. You should feel the knob dislodge slightly.
With the pin pulled back, release the saw arm and allow it to rise. Once it has reached maximum height, release the pin.