interior ceiling panel has rippled after leak, how to fix

[barbshortie]

The inside ceiling panel has 'rippled' after leak at the seam above.
The leak has been repaired. Is there a way to get the covering to go back tothe way it was? Someone told me you might be able to use a hair dryer to shrink the covering back? Anyone have any info?

[Alley_Fox]

Is it the usual vinyl coated board? You might try an iron starting out on a very low setting and use a piece of baker's parchment between the iron and the tile? That's what I would try, very cautiously of course....