Your brother can buy it as a foreign national with 50% down. If you speak to a local mortgage broker, I would assume they know which banks locally where they can place foreign national loans. These are not from the big lenders, but smaller local banks often do it.
Do you have income from any other source besides your brother? Does he really want to buy this for himself and use it as a second home? Because you are not being totally clear, we have no idea what you use as income. obviously you have something, unless it is just spending your own assets.