The volume shows up on screen and will not go off or work properly

Check for a leaky tact switch. You can do this by unsoldering the switches controlling the volume up and down on the keypad in the TV, not the remote, and swap them with the ones that control the channel up and down. (or just replace the two tact switches controlling the volume with new ones) If that does not change the condition, check for a pinched wire harness going from the keypad to the main board. If nothing found and the condition is still the same, then check for leaky diodes, sticky substances, or out of tolerance resistors on the keypad. If they all check OK and the problem is still the same, then you likely have a main board problem.