I am not using any external source. The only thing plugged into my TCL TV is the power plug. Three days ago I turned the TV off when I left the house; it was working perfectly. I came home and the TV was on, but there was no sound. I noticed a 34 code, and Googled for help. It took every fix except the factory reset to get my sound back. I used the TV 4 times, and yesterday the sound went again ... this time I have a 20 message which makes no sense to me.
In fact, the whole thing makes no sense, but any suggestions you have on how to trouble shoot would be much appreciated. The ROKU guys were stumped, as is Customer Service at TCL.