Were they labled as returns? Returns have a high likelyhood that there can be few or many damaged items in a lot. The note that you only recieved a few headphones tells me you bought a lot of returns.
When you buy items labled as returns in the electronics field its highly possible you will get basically returns without all the parts and accessories originally included in a new item. As I have always stated when buying from liquidation.com you must research the product condition and information fully before bidding. They are a clearance company and they clear literally anything. Also professionals buy damaged item lots all the time to fix them and resell them.
Contact liquidation.com and file a report if this is not the case. They usually contact you within 48-72 hours.
Also I think you definately paid way more for them then they were worth to begin with. Ive seen many auctions go for much less. As low as $45 a unit.
I would have to see the listing myself to know the facts but most of the liquidation.com listings I have seen they will tell you in the manefest if they powered on.
This link is an example.
Link hidden: Login to view
If your auction had a manifest. Double check it with your items and if it is incorrect then you have a case.
Just a note. You can still sell broken items on ebay. I do it all the time. Just make sure your listing shows you are selling broken units. I used to sell broken Xboxes for about $30 bucks less then the average selling price on ebay.