What is the make and model of the soundbar? Also when I installed the optical cable there were plastic coverings on each end to protect the cable. These must be removed before you plug the cable into the TV and the soundbar. On the cable I have if I unplug it from the soundbar and leave it connected to the TV with the TV power on, I see a red light at the end of the cable that gets plugged into the soundbar. This lets me know I have a good connection to the TV.
If your soundbar came with a remote, check the remote to see if there is a button to select source. On my soundbar I can cycle through the different sources and I only get sound when I select "OPT" - which is the way it should be.
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