I googled and tried all the suggestions when I warped my Olfa mat, sadly even though some of them looked like they were working, once the mat was placed flat on a surface again, up it popped. I tried soaking it in the tub and laying flat on concrete...I tried laying it in the hot sun on flat concrete and then piling books on top until the next morning...hmm... I'm sure I tried a few more, but good luck and maybe something you try just might help yours. Is it an Olfa ?