Perform the following steps if the no signal message remains.
Lg tv not connecting to cable box.
Shut the tv off and securely connect the cable box hdmi cable to hdmi 1 on the tv.
Unplug the power to the external device for 30 seconds.
Check that the external device is connected to the tv with an hdmi cable and is powered and switched on.
Make sure the other end is secure in the cable box.
Press the smart button on the remote control and select settings option set the universal control on the tv menu press wheel or enter to continue.
Some users have had success using the lg bluetooth rolly keyboard but this is not officially supported.
Plug the device back in and power the device back on.
Now please try this.
Bluetooth mice and keyboards are not supported.
If your remote has an input source button press it and choose the input from the list that matches where your device is connected.
Disconnect the cable box from power for 10 seconds to reboot it then plug it back in.
Simply connect your usb cable s to any available usb ports on the tv.
Disconnect the hdmi cable from the tv and move it to an alternate port.