I hope you might be able to recommend a way that I can repair the underlayment (or backing board) of a water damaged laminate counter top (actually it's the backsplash).

My laminate backsplash (just beneath the kitchen window) became wet. The particle board backing (underlayment) became wet and absorbed the moisture.
The particle board swelled thus causing the laminate to bulge. Both the laminate and backing board are now bulged.

How do I repair this mess? I need to know what I must do to flatten both the laminate layer and the backing board (particle board).

Let me know your recommendations.

Thanking you in advance for your help.