Most cabinet doors are glued together panels...using steam will ruin the glue joints. The safest approach is after taking panel to bare wood place the panel on a sheet of plastic on a work bench concave side up. Thoroughly wet top side of the panel and clamp down flat or shimmed to remove spring back. Keep wetting the wood over the course of a few days. Using the table of a 10" contractor table saw makes clamping really easy.
