Something fell off my bin when it was opening and now it won't close , how can I trouble shoot . I service it evey year and just did this summer . Thanks

something fell off my bin

Don't know what that means but suspect that it means that something hit one of the door sensors that send and receive the light beam across the opening. Realign the sensors. If the light beam is not received by the receiver, that is interpreted as something is in the doorway and the door will not come down.