It's always so discouraging when this happens to a new mattress! It's happened to me as well.
Try this simple recipe and see if you are pleased with the results:
In an empty spray bottle, mix:
8 oz (1 cup) hydrogen peroxide
3 Tablespoons baking soda
2 drops of dish soap
Several drops of lavender oil, if desired
Keep the bottle stirred, but don't shake too hard or it will want to bubble out of the bottle.
Saturate the entire urine stain with this mixture.
Let it soak it, and give it about an hour or so to dry.
Once dry, vacuum up any baking soda residue on top of the mattress.
Test to see if the stain is gone and the smell removed. If not, repeat again.
I hope this works for you.
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