If the colored LED lights on the door sensors are flickering then they are not "seeing" each other properly. The vibration of the motor might be moving them out of alignment. Or there may be some intermittent power issue, anything from a loose power outlet or cord to shorts in the wiring of the opener or to the sensors.
You might have other problems however, since the door sensors should not stop the door from opening. The sensors are there to protect against the door closing on something so they should have no effect on opening. And you almost certainly have some mechanical issue if you can hear the motor running but the door does not raise since the two are essentially connected to each other at all times (unless you release the door with the release rope on the door trolley).First, disconnect the door using the release rope and try lifting it by hand. If you cannot lift the door then you have some problem with the balance of the door/springs or something is binding in the door or the door rollers. A properly set-up door will not be overly hard to open and will stay half-way open on its own if you release it at that point.If the door set-up tests okay, see if the opener will move the lift trolley now that the door is disconnected. If not, and the motor is still running, something is binding or broken in the lift mechanism/trolley area or in the worm gear assembly that connects it directly to the motor under the opener cover.Looking at the exploded view of the motor assembly in your manual or on the Sears parts site will give you a better idea where those components are located and what might be involved in repairing them.- To view the Owner's Manual online -Go to the Home page of Manage My Home and hold your mouse over the square labeled HOME in the upper left of the page. A drop-down menu will appear, choose the option Products and manuals and then enter as much information as possible in the search option boxes that come up.