Hi,
When I had a similar problem with a BD 550 Sony player, I found cycling the input 'mode' back around to 'auto' sorted it out.
It's the button in the group underlined with the name 'input' and marked 'mode', near the phono connector (behind the front panel 'flap'). It would probably work left back on 'PCM' too as well
That assumes the the player is successfully outputting PCM, and the the input selected has been configured for HDMI, but it sounds like you already had that side going at one point...
Ken B.