Using sauté mode, heat oil in a multicooker. Add mushrooms, onion powder, and salt. Cook, stirring until the mushrooms have released their liquid, about 6 minutes. Add sherry and cook until mostly evaporated, about 1 minute. Stir in green beans and broth. Turn off sauté mode. Close and lock the lid and cook on high pressure for 3 minutes. Carefully release the pressure manually.