Have them show you it working at the store. If they can't show it working, then go for a full refund.
Just brought home a second Samsung Sound Bar HW-F550 after the first one did not produce any display or sound and did not work with the included remote. This one does produce sound but has no display and the remote controls the TV mute, volume, input but does not operate the sound bar at all. The Sound Bar is connected to the TV by an optical cable purchased at Best Buy at the time of purchase of the sound bar and a new Samsung TV. I can't believe I could purchase 2 bad speakers within 24 hours....could I be doing something wrong here? (I have done the troubleshooting suggested by agents at Samsung 1-888 # and they only suggested shipping it for service both times...quite a hassle for something that has never worked in the first place!!)