My Bad T 748 has power but will not send sound to the speakers . Please help .

I’ve had my receiver for 3 years and it has worked fine . Today It will power up but not send sound to the speakers . I have tried changing the HDMI chords. Could it be the HDMI port that is broken ? Or is it a fuse maybe ?
Post removed 
Or else the HDMI board failure or HDMI switching issue. very common issues with NAD av receivers & HT processors.  NAD home theater gears (AV receivers & processors) are well known for that. they are buggy, so are Rotel's & Cary Cinema 11 & 12 processors.
Don't get me wrong they all sounded great especially for music but are buggy. 

Unlike those Japanese AV receivers & processors that are reliable and aren't buggy but don't sound as good as the NAD or Rotel or the Cary Cinema.