[Blink]

So have you received a reply since you emailed them last?

If not, shoot off another "friendly reminder", politely asking where they're at with the replacement.  Make sure to Include the term "replacement" In your email- just so they're aware that a replacement Is what you're expecting. The objective Is to get them on your side, empathize what you're going through and finalize your request.

They haven't replied yet. I'd rather wait another day before doing that or it'll make me seem desperate and pushy. What do you think I should say?

"Hello I sent you an email about the Liberate XLBT headphones. I was wondering where your at with the replacement. I don't want to go out and spend another 200 dollars on headphones knowing that they'll break again and it's not replaceable."
good enough?

If you know they'll break again, why would you want a replacement?

At this point they are suspicious. Tread lightly.
Regarding the pictures, just say that you threw the headphones out because of the danger. Emphasis 'how afraid you were'.