They'll probably offer you a replacement P/S box, and charge it from your card.
After you've shipped back your old one they'll refund the money.
At least that's how they offered to handle the warranty on my leaky P/S box. Sounded fair to me.
I declined and fixed it myself because the hassle of shipping it back (and still not being able to drive because of the leaks) wasn't worth it for me.