Our shop has a client that wants us to repair an 36"x96" HDU panel we installed 2 years ago. The sign still looks great but has started to cup away from the wall. They sign was painted with Matthews 6001 polyester primer a satin map paint. We made sure at the time to evenly coat all sides. Other signs we have produced are fine and this one seems to be a one off. Is there any good way to unwarp the panel? We were thinking of heating the panel back flat and applying another coat of paint to the back.