lg bd570 hdmi not working

Recently I bought a lg bd570 from tiger direct for $20.00(open item as is). Everything on it works except the hdmi port. When I connect it up via the component cables(component only does 1080i)it works with no problems(plays every disc format I throw at it (even has Netflix, Vudu, YouTube, Roxio CinemaNow, Pandora, Picasa, AccuWeather). Even the WiFi and Ethernet port works! But when I boot it up using a hdmi cable, it shows the lg boot screen and then a black screen(no matter what HDMI tv I use/ cable. I have been searching for a short time on line to see if there is answer to why it would do that, and haven't really found an answer. Is 1080p better than 1080i? I think it looks great over 1080i, but my older brother insists that 1080p looks better.

http://www.lg.com/us/blu-ray-players/lg-BD570-blu-ray-dvd-player