Hi Harry o, If your TV has a black screen even when it's on, it's quite possible it could actually be your external device and not your TV. Please try these troubleshooting steps for your blank screen issue: 1. Press the Home button on the remote. If the menu appears, the TV is powered on but is either not on the correct source or not receiving a signal. If the menu does not appear, the TV may be having power issues. Check the red standby light, a little red light at the edge of the TV that you aim the remote at. In normal use, the red standby light is on when the TV is off (indicating the TV is on standby), and the red standby light is off when the TV is in use (or doesn't have power). 2. Confirm that the TV is set to the same source as the external device. For instance, if your cable box is connected to HDMI 1, set the TV source to HDMI 1. If the TV is set to the correct source, but there is still no image, unplug and reconnect the AV connections one cable at a time from both ends of each cable. If there's any damage to the cable, it will need to be replaced. After reconnecting the external device, please turn it off and back on. 3. Test the HDMI cable. The test is designed for HDMI cords less than 6 feet long and may not give accurate results on longer cords. To perform the test, make sure the TV's source is still on the HDMI setting for the cable you want to test, and then navigate to Settings > Support > Self Diagnosis > Signal Information > HDMI Cable Test > Start Test. If the test says the cable is bad, replace the cable. Service is not required. 4. Test different external devices. The final thing to rule out is the external device you're using. Try connecting a different device or using a different source port. If the TV can display a picture in any other setup, then you've ruled the TV out as the cause of the issue. Keep trying various setups until you identify the device or cable that is not working and troubleshoot or replace it. The TV will need service if the issue persists after these steps. Please contact us so that we can better investigate your issue and assist you with a solution or replacement. If you need more help, Samsung is here for you! Please call us at 1-800-SAMSUNG, 8 AM - 12 AM EST, seven days a week. Our LiveChat agents are also available by clicking on the ‘Support’ link on our website. ~ Samsung Advisor