If it do not receive any signal, the tuner to this TV should be suspected. Anyway, if you wish to make it to factory reset, you have to enter its service mode option, and should select the Factory Reset option, to go further.
If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. Do a search by type in the brand name of your device at its search box and press "Enter".