Each rotating part of the robot is a hinge with an axle. The Hinge limits can be seen by setting 3D View > render > hinges to Always.

Select a hinge in the Scene tab.

Notice the selected hinge becomes larger in the 3D view to make it stand out. The yellow area is the allowed range. The white line is the current position.

Adjust the minimum and maximum. If the max is 360 and the min is 0 then the hinge will be unrestricted.

Repeat for every hinge in the robot.