Try this to restore the tv to normal. Be aware of which buttons to use wrt the TV panel or remote control.
Press and hold [MENU] on the TV and [RECALL/COLOUR SYS] button on remote to display the Dealer Mode
menu. Use [CH ^/v] on TV and select RESET in the menu. Press [VOL ^/v] on TV to start the reset. Press
[OK] on the remote to confirm the reset. When complete, press [MENU] on the TV to exit.