I'm sorry that your DU7200 TV will not turn on. Please know we are here to help and have a few troubleshooting tips for you to try.
Check the red standby light, a little red light at the edge of the TV that you aim the remote at. If it is on, it means that your TV is receiving power, and the culprit is likely the remote. Please try to power the TV on through the button below the Samsung logo. If it powers on, I recommend changing the batteries on the remote and possibly replacing the remote.
If the red light below the TV is not on, please try the following:
1) Unplug the TV from its power source for 30 seconds. Then try to power it on again.
2) Try a different outlet that you have confirmed works properly
3) Press the Menu button on your remote. If the Menu appears, then this confirms your TV is powered on. Next, follow these steps:
・Confirm that the TV is set to the same source as the external device.
・Test the HDMI cable. Go 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.
・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.
Finally, if the red standby light is blinking, please try unplugging the TV for 30 seconds and then try again. Also, confirm that the outlet you are using works with other devices.
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 Ambassador