Start small
Down can feel vulnerable for some dogs, so the first steps should feel easy and optional.
There is no need to rush. A predictable, manageable step is usually more useful than trying to solve the whole situation in one day.
Try this next
Guide a reward from the nose toward the floor and reward any relaxed movement downward.
Notice what helps your dog stay comfortable and engaged, then repeat that version before making the situation harder.
Keep it kind and practical
Keep the next step easy enough that your dog can succeed. If you are worried about safety or feel stuck, pause and ask a qualified reward-based professional for help.