Not quite "disaster" material, but I would heat it with a hair dryer or a tub of hot water and then set heavy boxes on it for a few days.
Have an electric blanket or heated mattress pad? Either could be made use of to warm the thing before allowing it to cool while under something heavy.
Or call the manufacturer and ask.

Seeing as it took the curled shape in room temperature I'm betting just something heavy and flat on top of it for a week would probably do it even without the warmth.