Scrappile is right about the planer. It will not flatten a warped board. The cupping is caused by uneven drying. If the cupping is severe you may not be able to salvage piece. The way I understand it, the wetting of one side or section was for plywood, I may be wrong on this. I would try soaking the piece and adding weight to the areas that are cupped. You have nothing to lose if the piece is short. On thicker pieces I use a hand plane to remove the cupping then can run it through my planer to a desired thickness. Personally I don't like losing exotic woods in my shop. When I stack my stock, I keep the thinner pieces on the bottom, this keeps weight on it and helps prevent cupping. It is a pain to move a lot of stock to get the piece(s) you want but seems to save on wasted pieces you can not use. Hope you find the ideal answer and manage to save all you can. I'm sure others will chime in also with different ideas.