The tv is likely in childlock mode. To get into or out of this mode you need the original remote or it similar replacement. Then you need to hold the F key and press MUTE. This will set the device into or out of this mode. This also works on Classic brand sets.
B. A. Tetreault
March 2010
you need remote control
Lianne
March 2007
I can answer this question...
how do i get a schneider ctv2701 out of lock mode?