Thank you for posting your question on Just Answer! I will be happy to help you with this problem. Can you please give us some more information so I can better answer your questions.
-How old is the unit?
- Do you have this problem while watching all different devices hooked to this television? (DVD player, cable, satellite, game counsel, ect.)
Please give me this information and I will be happy to assist you further.
It is about 5 years old. Only a U-verse box is hooked to it and it cannot display anything because the TV child lock is on. Nothing can be seen on this tv except the key in lower left corner.
Sorry, I cannot find a manual on this set, let me see if any other experts have one.
Yes, that's fine. So you know, we have tried holding down the F button and then pressing Mute, to no avail.
We will not touch anything else other than what you tell us.
Sorry, no luck yet. I pushed the decrease-volume button on the remote(the Apex remote, not the U-verse remote) several times to take it to zero, although I could not see this on the screen due to the problem.
Then I followed Step 2 exactly but "S" never appeared. The key still is in left corner.
I unplugged the U-verse box just in case it was interfering and then repeated the above but to no avail.
We normally use only the U-verse remote to turn on the tv and adjust the volume. Should we try using it for the above steps?
Thanks for all your help. We will turn off the tv for a day and see what happens. You had more good ideas than anyone. We appreciate your efforts and we are accepting your answer. Thanks,