A frightened and panicked bird stuck in the garage may fly erratically and bounce off the rafters and walls often circling the light. Turn the garage light off and draw the bird through the garage door with additional lights outdoors. If there is no light on in the garage, make the garage as dark as possible by closing additional doors and shading windows. Then, open the main door and the bird should fly towards the light source outside.
There are commercially available repellants marketed for bats that often contain natural plant-based oils like peppermint or geranium oil. However, these typically are ineffective. The odor doesn't last long, it takes a lot to properly treat an attic, and attics are typically ventilated which diminishes the effects. In addition, they may cause a strong odor in your home that is unbearable.