Doublecheck your setup at https://sony-paa-pa-en-web--paa.custhelp.com/app/answers/detail/a_id/148429/session/L3RpbWUvMTQ4MTU3MzYzOS9zaWQvUjZOMjZaNW4%3D
Samsungs have a habit of being in Shop Mode and reset settings so check that again.
I read your post and if there is no sound at all from all sources the HT may be dead.
I just just bought a Samsung UA55KU6000 Tv and used a HDMI cable to connect it to my Sony Dav-dz640k home theater. everything worked perfectly for about 4 days and then i stopped hearing any sound from my home theater.Any possible solution?Thank You in advance.