Reply by TCCcabinetmaker

read above,

However if you want to flatten the panel first you can always put a block of wood on it, and strike it with a mallet, usually this will remove a bump, and the block will keep you from getting a dent! But if you get a dent, just get out a clothes iron, fill it with water, turn it as high as it will go and set it to steam, it’ll pull it right out.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.