If in bottles, the batch can be saved.
1. Place a nickel or quarter over the top of the cap to protect it from plastic deformation.
2. Place the bottle opener so that the point of leverage is on the coin.
3. Use the bottle opener to gently crack the crown seal and allow some pressure to escape. Keep an eye on the liquid level inside the beer bottle and don't let it reach the cap if it foams.
4. When you let the force off the bottle opener, the cap should re-seal and stop any foaming from getting out.
5. Use a bottle capper to reseal the existing cap.
6. This process will kick up the yeast sediment. Allow at least two weeks for everything to resettle at the bottom of the bottle before testing.
I have saved a batch of over-carbonated dubbel using this method. Nine months later, the beer is still great.
I would take precaution if it is over-carbed to the point where you fear bottle bombs. Wear long, thick sleeves, a face shield (or at least safety goggles). Use a plastic bin to contain the bottle as best you can. Serious injury can occur.