That's the biggest problem about dealing with dropshippers..
And most likely by the time you do hear back from your dropshipper, your buyer is probably going to have file a dispute with ebay and paypal if they paid that way..
You need to get on the phone with your supplier and get some answers..Next I would probably try to get the buyer a replacement or give him a refund..
As far as the chair being received in 'brand new' condition, does not mean that it was not broken..I purchased a brand new camera at christmas and it arrived not working, but it was brand new and sealed in the container...
Keep in contant with your buyer and try to work it out with him, most people are understanding and will work with you if they see you are trying to honor your end of the deal..But I would not rely on email to try and talk with the dropshipper,, you need to use the phone and talk with them and find out your options as quickly as possible..