If your remote has an input source button press it and choose the input from the list that matches where your device is connected.
Lg tv not connecting to cable box.
Disconnect the cable box from power for 10 seconds to reboot it then plug it back in.
If your remote does not have an input source button press the home button then look in the upper right corner of the tv for the input icon and click it.
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.
Shut the tv off and securely connect the cable box hdmi cable to hdmi 1 on the tv.
Once the box has rebooted turn the tv on and use the lg remote s input button to select hdmi 1.
Unplug the power to the external device for 30 seconds.
Disconnect the hdmi cable from the tv and move it to an alternate port.
Some users have had success using the lg bluetooth rolly keyboard but this is not officially supported.
Change the tv to the new hdmi input to see if the issue.
Perform the following steps if the no signal message remains.
Plug the device back in and power the device back on.
Make sure the other end is secure in the cable box.
Simply connect your usb cable s to any available usb ports on the tv.