Sorry but I don't dive into consumer product repairs anymore. (long story) But I will share ideas when possible.
Look around for any firmware update on the LG site. Install that and hope. Be sure that something else works on the end of the HDMI cable that plugs into the BD player. That is, unplug from the LG and into something else as a test.
Bought LG BD570 Mar 2010 - worked fine for about 8 mo, then only displayed "HELLO" on DVD player and blank Sony Bravia TV screen. Tried new HDMI cables, reset player according to manual, then called and emailed LG customer service. Useless e-mail reply but phone rep gave me a more complicated series of steps to reset player to rescan my TV. Did that twice and still no go. Now I have to send it back (warranty only good now for parts so it'll cost me $69 plus). Any ideas?