What's wrong with my crushers? Low sound no bass

Not long ago my dog was a pup and when I came home he had my Skullcandy crushers in his mouth. At first I thought he just shredded the ear cups but I was wrong. They've had low sound and no bass at all with or without the slider up. My boyfriend had got them for me as a gift and not long there after he killed him self. These headphones are dear to me and I won't get rid of them and I don't have the paper work or whatever I probably need to have the warranty or whatever replacement. I want this pair repaired. I could probably do it myself if I figured out what the issue is idk where to start I don't want to just tear them apart and never get them back together