Recently we have found many Samsung TV's older than 4 years are having issue with continually restarting.  Issue is more prevalent on Samsung LED and LCD tvs from 2012. 

TV will start normally and after some time into watching TV starts restarting it self in endless loop. Some times just using any key on remote like Volume Up or Down button with start the boot cycle.

To resolve this issue we found below solution:

1. Issue due to new HDMI devices:

When you plugged a new FireHD or a new Streaming device like google chrome the issues stared. in this case its the issue with the universal Fire Remote or Chrome Remote. To resolve this issue reset your Fire HD stick and make sure not to add other devices like Blu-ray and sound bar to be controlled with fire HD remote. 

2. Over heating Samsung chip:

Samsung TV comes with a CPU, that can get really hot as the TV gets older, There is a heat sink attached to the chip that can easily slip.  Try touching the back of your TV next to HDMI ports. if you feel its too hot. Most probably its over heating. To resolve over heating. open the back panel of the tv to check if the heat sink has moved out of place. then peel off the sticker provided for Samsung extension package. This will resolve the over heating problem.

3. Damaged flat cable connecting the Main board and the LED control panel.

To fix this issue you need to open your TV, disconnect power before proceeding. using a Philips screw driver open screws located back of Samsung TV, using a pinch motion remove the flat black cable and wait for 60 seconds and put it back. connect the cable back in its place. fix the back cover. 
once you start the TV do not add wifi to the TV and you are good to go.

Now we are getting into weeds.

4. Damaged Power supply or blown capacitors :

to fix this you need to buy a parts, i would suggest to buy new board and replace it , individually fixing the components require soldering iron and the parts. 

5. Damaged Main board :

only solution is to replace the board itself.