To make a hard reset, just unplug the TV from AC mains wall socket, and re-plug it back after 15 minutes or so. This must make it a hard reset. If you wish to make a system reset, you have to enter its service mode option. To know more about this, check this link. It has details about how to enter, adjust and exit the service mode, to many brand TVs.
http://electronicshelponline.blogspot.com/
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